Ultrasonographic Investigation of Cleft-Type Compensatory Articulations

by

Bojana Radovanovic

A thesis submitted in conformity with the requirements

for the degree of Master of Science

Department of Speech-Language Pathology

University of Toronto

© Copyright by Bojana Radovanovic 2012

ii

Ultrasonographic Investigation of Cleft-Type Compensatory Articulations

Bojana Radovanovic

Master of Science

Department of Speech-Language Pathology

University of Toronto

2012

Abstract

Cleft lip and/or palate is a craniofacial condition that can lead to complex speech disorders. In

particular, the auditory-perceptual speech assessments of individuals with cleft palate can be

difficult because cleft-type compensatory articulations may be outside of English phonology.

Therefore, it is desirable to supplement auditory-perceptual assessments with instrumental

measurements. In the first study, thirteen participants with cleft-type compensatory articulations

completed ultrasound speech exams. The stimuli were repeated VCV combinations (target

consonants: [], [], [], [], [], []; vowel contexts: [], [], []). Ultrasound imaging confirmed

auditory-perceptual impressions and revealed covert articulatory movements. In the second

study, six participants were assessed after a course of speech therapy. Outcomes were recorded

on a severity metric with categories describing auditory-perceptual and motor aspects of speech

errors. The severity metric quantified the incremental changes in both dimensions. Based on the

research presented, further investigations of cleft palate speech using ultrasound are warranted.

iii

Acknowledgments

First and foremost, I am indebted to my supervisor, Dr. Tim Bressmann, for his patience,

encouragement, kindness and, of course, knowledge. This thesis would not have been possible

without him.

I am extremely grateful to Dr. Pascal van Lieshout and Dr. Gajanan K. Kulkarni for being such

supportive committee members. Their insightful criticism and guidance throughout this process

were critical. I would also like to acknowledge Dr. Aravind Kumar Namasivayam and Dr. Alexei

Kochetov for their advice as members of my defense committee.

I would like to thank the entire Voice and Resonance Lab team, and in particular Gillian de Boer,

Susan Harper and Christina Khaouli Tannous, for their help, friendship and support.

I am thankful as well to my many amazing friends, for their encouragement during strenuous

times. I am so appreciative of the emotional support they provide in all areas of my life.

My parents, Sasha and Jasmina Radovanovic, have been an unwavering source of support –

emotional, moral and of course financial – during all my years. It is to them that this thesis is

dedicated. And finally, a thank you to Nikola Radovanovic for being everything a little brother

should be.

iv

Table of Contents

Abstract ........................................................................................................................................... ii

Acknowledgements ........................................................................................................................ iii

List of Tables ................................................................................................................................ vii

List of Figures .............................................................................................................................. viii

List of Appendices .......................................................................................................................... x

1. Introduction ................................................................................................................................. 1

1.1 Cleft Lip and Palate ............................................................................................................... 1

1.1.1 Prevalence ....................................................................................................................... 3

1.1.2 Cleft Lip and Palate Embryology and Etiology ............................................................. 3

1.1.3 Cleft Lip and Palate Repair ............................................................................................ 5

1.2 Consequences of Cleft Lip and Palate ................................................................................... 6

1.2.1 Non-Speech Consequences of a Cleft ............................................................................ 6

1.2.2 Speech Consequences of Cleft Lip and Palate ............................................................... 7

1.2.2.1 The Velopharyngeal Mechanism ............................................................................ 7

1.2.2.2 Velopharyngeal Dysfunction .................................................................................. 8

1.2.2.3 Hypernasality and Compensatory Articulations ..................................................... 9

1.3 The Management of Cleft Lip and Palate Speech Problems ............................................... 10

1.3.1 Assessment ................................................................................................................... 10

1.3.1.1 An Instrumental Measure: EPG ............................................................................ 12

1.3.1.2 An Alternative Instrumental Measure: Ultrasound Imaging ............................... 14

1.3.2 Speech Therapy for Cleft-Type Compensatory Articulations ...................................... 15

1.3.3 Severity of the Speech Disorder ................................................................................... 16

1.4 Study Objectives and Rationale .......................................................................................... 18

v

2. Exploring Cleft-Type Compensatory Articulations Using Ultrasound Imaging ...................... 19

2.1 Participants .......................................................................................................................... 19

2.2 Methods ............................................................................................................................... 20

2.2.1 Materials ....................................................................................................................... 20

2.2.2 Data Collection ............................................................................................................. 21

2.2.3 Data Treatment and Analysis ....................................................................................... 22

2.3 Results ................................................................................................................................. 23

2.3.1 Stops ............................................................................................................................. 23

2.3.1.1 Results for the Alveolar Stop [] ........................................................................... 23

2.3.1.2 Results for the Velar Stop [] ............................................................................... 25 2.3.2 Fricatives ...................................................................................................................... 27

2.3.2.1 Results for the Alveolar Fricative [] ................................................................... 27

2.3.2.2 Results for the Postalveolar Fricative [] .............................................................. 29 2.3.3 Nasals ........................................................................................................................... 30

2.3.3.1 Results for the Alveolar Nasal [] ........................................................................ 30

2.3.3.2 Results for the Velar Nasal [] ............................................................................. 32

2.4 Discussion ........................................................................................................................... 33

2.4.1 Stops ............................................................................................................................. 33

2.4.2 Fricatives ...................................................................................................................... 35

2.4.3 Nasals ........................................................................................................................... 37

2.4.4 Clinical Implications .................................................................................................... 38

3. Developing and Evaluating a Scoring Metric for Cleft-Type Compensatory Articulations..... 40

3.1 Participants .......................................................................................................................... 40

3.2 Methods ............................................................................................................................... 40

3.2.1 Materials, Data Collection and Treatment .................................................................... 40

3.2.2 Intervention ................................................................................................................... 41

3.2.3 Scoring Metric .............................................................................................................. 43

vi

3.2.4 Data Analysis ................................................................................................................ 45

3.3 Results ................................................................................................................................. 45

3.3.1 Stop [] .......................................................................................................................... 46

3.3.2 Stop [] ......................................................................................................................... 48

3.3.3 Fricative [] .................................................................................................................. 50 3.3.4 Average Change ........................................................................................................... 52

3.4 Discussion ........................................................................................................................... 53

4. Limitations ............................................................................................................................... 55

5. Conclusion ................................................................................................................................ 56

7. References ................................................................................................................................. 57

Appendix A ................................................................................................................................... 71

Appendix B ................................................................................................................................... 77

vii

List of Tables

Table 1. Information about cleft type, age and sex of the participants in Study I.

Table 2. Vowel-consonant-vowel stimuli used.

Table 3. Summary of participant realizations (%) for the alveolar stop target [].

Table 4. Summary of participant realizations (%) for the velar stop target [].

Table 5. Summary of participant realizations (%) for the alveolar fricative target [].

Table 6. Summary of participant realizations (%) for the postalveolar fricative target [].

Table 7. Summary of participant realizations (%) for the alveolar nasal target [].

Table 8. Amount of clicking (%) accompanying the nasal targets [] and [].

Table 9. Summary of participant realizations (%) for the velar nasal target [].

Table 10. Study II participant information.

Table 11. Severity scoring sheet for [t].

Table 12. Severity scoring sheet for [k].

Table 13. Severity scoring sheet for [s].

Table 14. Speech severity of 6 participants before and after biofeedback speech

therapy. The average change per participant and across participants is shown.

Table 15. Auditory-perceptual and visual judgments of realizations produced by 2 participants

before and after biofeedback speech therapy for the alveolar stop [t].

Table 16. Auditory-perceptual and visual judgments of realizations produced by 2 participants

before and after biofeedback speech therapy for the velar stop [k].

Table 17. Auditory-perceptual and visual judgments of realizations produced by 2 participants

before and after biofeedback speech therapy for the alveolar fricative [s].

viii

List of Figures

Figure 1. Examples of the different severities of cleft lip and palate: (A) an incomplete unilateral

cleft lip; (B) a complete unilateral cleft of the lip and alveolus; (C) A complete bilateral cleft lip

and palate; (D) a complete cleft of the palate only. [www.biomedcentral.com/content/figures/

1471-2350-5-15-1.jpg]

Figure 2. Clefts of the lip: (A) incomplete unilateral cleft lip; (B) complete unilateral cleft lip;

(C) complete bilateral cleft lip. [www.facesofchildren.org/Condition Descriptions]

Figure 3. Clefts of the palate: (A) incomplete cleft palate; (B) complete cleft of the soft and hard

palates. [from: Silva Filho, O.G., Rosa, L.A, & Lauris, R.C.M.C. (2007). Influence of isolated

cleft palate and palatoplasty on the face. Journal of Applied Oral Science, 15, 199-208. Figure 1.

Reprinted with permission.]

Figure 4. The respective contributions of the primary palate (light grey) and the secondary palate

(dark grey) to the completed palate during palatogenesis. [www.motifolio.com/1011244.html]

Figure 5. The velopharyngeal mechanism, when open (A) and closed (B). [modified from

http://quizlet.com/6060746/5070-121-test-3-velopfunction-flash-cards/]

Figure 6. The three basic velopharyngeal closure patterns. The black triangles represent the

magnitude of contribution of each sphincter component to the closure mechanism. [modified

from: Poppelreuter, S., Engelke, W. & Bruns, T. (2000). Quantitative analysis of the

velopharyngeal sphincter function during speech. Cleft-Palate Craniofacial Journal, 37, 157-

165. Figure 4. Reprinted with permission.]

Figure 7. Placement of common cleft-type compensatory plosives: (A) a midpalatal stop; (B) a

pharyngeal stop; (C) a glottal stop. [modified from: Trost, J.E. (1981). Articulatory additions to

the classical description of the speech of persons with cleft palate. Cleft Palate Journal, 18, 193-

203. Figure 4. Reprinted with permission.]

Figure 8. Vocal tract configuration during common cleft-type compensatory articulations. (A)

the posterior nasal fricative: the tongue creates a constriction at the back of the oral cavity while

the velum flutters to produce frication. (B) a double articulation: the articulation here is of an

alveolar and glottal plosive where the air is stopped both at the alveolar ridge and at the glottis.

[modified from: Trost, J.E. (1981). Articulatory additions to the classical description of the

speech of persons with cleft palate. Cleft Palate Journal, 18, 193-203. (Figure 4) Reprinted with

permission.]

ix

Figure 9. Electropalatography palates from a variety of models: (A) the embedded electrodes;

(B) the wires and connector; and (C) the positioning within a participants mouth. [modified from:

http://rose-medical.com/linguagraph.html, http://achiralblog.learn-alesson.com/2008/02/

electropalatography.html, and http://utlinguistics.blogspot.ca/2010_02_01_archive.html]

Figure 10. Single electropalatography frames from a normal speaker for the fricatives /s/ and // and the plosives /t/ and /k/.

Figure 11. A single frame of an ultrasound video, with a sagittal tongue view insert to show the

orientation. The curved white line in the ultrasound image represents the tongue surface.

Figure 12. The ultrasound scanner (A) and Comfortable Head Anchor for Sonographic

Examinations (B) used during the assessment protocol.

Figure 13. A frame from the clip of Sabrina’s production of [] showing a 2-point elevation (arrows) during target realization.

Figure 14. Using ultrasound as biofeedback speech therapy: (A) the image display; (B) setup

during a therapy session.

Figure 15. Radar graph displaying severity scores for Stella before (dark grey) and after (light

grey) biofeedback speech therapy for the alveolar stop [t].

Figure 16. Radar graph displaying severity scores for Sally before (dark grey) and after (light

grey) biofeedback speech therapy for the alveolar stop [t].

Figure 17. Radar graph displaying severity scores for Sandra before (dark grey) and after (light

grey) biofeedback speech therapy for the velar stop [k].

Figure 18. Radar graph displaying severity scores for Sofia before (dark grey) and after (light

grey) biofeedback speech therapy for the velar stop [k].

Figure 19. Radar graph displaying severity scores for Sabrina before (dark grey) and after (light

grey) biofeedback speech therapy for the alveolar fricative [s].

Figure 20. Radar graph displaying severity scores for Steve before (dark grey) and after (light

grey) biofeedback speech therapy for the alveolar fricative [s].

Figure 21. Speech severity of 6 participants before (dark grey) and after (light grey) biofeedback

speech therapy.

x

List of Appendices

Appendix A: Severity Scores.

Appendix B: Within-Participant Variation.

1

Chapter 1 Introduction

The repercussions of a cleft lip and/or palate on an individual’s speech can be considerable.

Structural issues, physiological dysfunction and speech mislearning can all affect articulatory

patterns, resulting in cleft-type compensatory articulations. The auditory-perceptual assessment

of these errors can be difficult because their sound patterns may be hard to recognize (based on

standard English phonemic representations) and are often complex co-productions. Therefore, it

is desirable to supplement auditory-perceptual assessments with instrumental measurements. In

the present study, the use of medical ultrasound imaging for this purpose was evaluated.

Ultrasound imaging can be a safe, simple and relatively inexpensive adjunct to traditional

assessment approaches.

Current assessments of cleft type speech also lack the ability to capture gradual improvement,

even though partial improvement in articulation can be a common outcome of speech therapy for

cleft palate. There is a need for a measure of therapy progress that can report incremental

changes and that can take motor aspects of the speech production into account. It would likewise

be useful to have an overall measure of severity of cleft-type compensatory articulations. In the

present study, this need was addressed through the development of a tentative scoring metric

which was tested with six participants before and after speech therapy.

1.1 Cleft Lip and Palate

Cleft lip and palate (CLP) is a congenital craniofacial deformity arising from atypical

development during the gestational period. It is one of the most common birth defects, occurring

in approximately 1 of every 540 live births in Canada (León & Rouleau, 2006; Slator et al.,

2009). Instances of CLP are typically grouped into 2 categories: cleft lip with or without cleft

palate (CL+/- P) and cleft palate alone (CPO). These groupings are based on the embryological

processes from which they arise (Peterson-Falzone et al., 2001). Around 50% of CLP cases

involve both the lip and palate, while a cleft of the lip alone and a cleft of the palate alone each

account for 25% of CLP cases (Gorlin & Baylis, 2009). Figure 1 demonstrates different

examples of cleft lip and/or palate.

2

Figure 1. Examples of the different severities of cleft lip and palate: (A) an incomplete unilateral cleft lip; (B) a complete unilateral cleft of the lip and alveolus; (C) A complete bilateral cleft lip and palate; (D) a complete cleft of

the palate only. [www.biomedcentral.com/content/figures/1471-2350-5-15-1.jpg]

A cleft of the lip can be classified as unilateral, where the cleft is present on only one side of the

lip, or bilateral, where both sides of the lip are involved. Additionally, lip clefts can be either

incomplete or complete, depending on if the cleft extends through the floor of the nostril (Figure

2). More often than not, a cleft lip is accompanied by a cleft of the alveolus (Peterson-Falzone et

al., 2001; Mossey et al., 2009). For unknown reasons, an isolated cleft lip is more often unilateral

(in 80% of cases) and occurs more frequently on the left side (in 70% of cases). However, the

majority of both bilateral and unilateral cleft lips are associated with a cleft in the palate (85%

and 70%, respectively) (Gorlin & Baylis, 2009).

Figure 2. Clefts of the lip: (A) incomplete unilateral cleft lip; (B) complete unilateral cleft lip; (C) complete bilateral cleft lip. [www.facesofchildren.org/Condition Descriptions]

3

A cleft of the palate is a midline fissure in the hard and/or soft palates (Figure 3). Similar to cleft

lip classification, a cleft palate can be complete or incomplete, depending on whether there is

tissue present across the line of the cleft (Longacre, 1970; Mossey et al., 2009). Clefts in the

palate also vary on 3 additional dimensions: 1) the anterior-posterior dimension, where palatal

clefts can be of the soft palate alone, the soft palate and some portion of the hard palate, or the

entirety of the soft and hard palates; 2) the lateral dimension, where a cleft varies in its width;

and 3) the depth dimension, where clefts can be present on either – or both – nasal and oral

surfaces of the palate without penetrating completely through the bone and muscle (Peterson-

Falzone et al., 2001). There are also several types of minor clefts of both the lip and palate, such

as microform and submucous clefts (Stal & Hicks, 1998; Gorlin & Baylis, 2009).

Figure 3. Clefts of the palate: (A) incomplete cleft palate; (B) complete cleft of the soft and hard palates. [from: Silva Filho, O.G., Rosa, L.A, & Lauris, R.C.M.C. (2007). Influence of isolated cleft palate and palatoplasty on the

face. Journal of Applied Oral Science, 15, 199-208. Figure 1. Reprinted with permission.]

1.1.1 Prevalence

Cleft lip with or without cleft palate is more common in males, while females seem to be more

vulnerable to cleft palate alone (León & Rouleau, 2006). Rates for clefts of the soft palate alone

are not affected by sex (Gorlin & Baylis, 2009). In addition, rates of cleft lip with or without

cleft palate are highest in individuals of Asian descent, while rates of isolated cleft palate are not

affected by race (Peterson-Falzone et al., 2001).

1.1.2 Cleft Lip and Palate Embryology and Etiology

During normal gestation, facial development occurs between the 5th

and 12th

weeks (Peterson-

Falzone et al., 2001). The initial steps involve neural crest cell migration to appropriate regions

and at appropriate times. The entirety of the facial bones and tissues develop from these cells.

4

The neural crest cells form several preliminary structures which fuse to create the primary and

secondary palates (Figure 4). The primary palate – responsible for the formation of the middle

section of the upper lip, the alveolar ridge and the premaxilla (the anterior 10% of the hard

palate) – results from the fusion of the median and lateral nasal processes with the paired

maxillary prominences. This occurs during the 6th

week of gestation (Longacre, 1970; Gorlin &

Slavkin, 1997). The secondary palate forms the other 90% of the hard palate and the entirety of

the soft palate. It is a result of the fusion of the palatine shelves (Gorlin & Baylis, 2009). The

palatine shelves first elevate from their initial vertical positions into a horizontal arrangement so

that they can approximate and fuse, and this occurs between the 10th

and 12th

weeks of gestation.

Fusion of the palatine shelves proceeds from front to back. The completed secondary palate also

fuses with the primary palate, the nasal septum and the vomer bone to create the final palatal

region (Merritt, 2005; Kummer, 2008).

Figure 4. The respective contributions of the primary palate (light grey) and the secondary palate (dark grey) to the completed palate during palatogenesis. [www.motifolio.com/1011244.html]

A breakdown in any of the above mentioned steps can account for the development of a cleft lip

and palate. A lip cleft is the result of a failure during the proper development of the primary

palate, while a palatal cleft stems from a failure of the proper development of the secondary

palate (Merritt, 2005). Although the primary and secondary palates follow distinct paths of

development, they both rely on the same types of processes, including proper neural crest

migration, appropriate growth of embryonic structures and correct fusion of these structures.

Insufficient or failed migration of the neural crest cells is a likely cause for both lip and palatal

clefts (Peterson-Falzone et al., 2001). Similarly, inadequate growth of any of the involved

processes could be to blame since it can result in the failure of the processes to articulate and

thus fuse properly. By the same token, a failure of the palatine shelves to elevate at the proper

time can influence the proper development of the secondary palate (Kummer, 2008). There may

also be complications during fusion itself: for example, fusion of the palatine shelves relies on

5

programmed cell death at the shelf edges, and if this cell death is impaired then fusion is likewise

impaired. Interestingly, palatine shelf elevation and fusion seems to last a week longer in female

than in male embryos, which could account for the higher prevalence of isolated cleft palate seen

in girls relative to boys. A post-fusion rupture can also occur, in which an already developed

seam between bones breaks down (Gorlin & Baylis, 2009). Overall, development follows a

threshold concept wherein the right timing and placement is crucial to typical development. If a

certain period within which an action was supposed to take place is passed, that action (in this

case fusion of embryonic processes) may not happen. Fundamental to the severity of a cleft is the

principle that the earlier a disruption happens, the greater the effect that disruption will have.

Therefore, insufficient growth of the palatine shelves, for instance, is more likely to result in a

wider, longer and/or deeper cleft of the palate than a disruption in the fusion of the palatine

shelves (Longacre, 1970; Peterson-Falzone et al., 2001).

The reasons for these breakdowns in typical development come from numerous areas. Both

CL+/-P and CPO are etiologically heterogeneous defects (Gorlin & Baylis, 2009). Clefts can

often be attributed to purely genetic factors. For instance, a single gene is responsible for

conditions such as Treacher-Collins Syndrome, Stickler Syndrome, and Van der Woude

Syndrome, and these disorders often include a cleft of the palate (Peterson-Falzone et al., 2001).

Certain chromosomal disorders, including Velocardiofacial Syndrome, are often accompanied by

a cleft, and parental age has also been linked to an increased risk for clefts (Stanier & Moore,

2004; Kummer, 2008). However, no one model can explain all instances of clefting. As is the

case with other complex conditions, a cleft will develop if enough factors – whether genetic,

environmental or both – are present. Environmental factors that may put embryos at an increased

risk for the development of a cleft include maternal intake of folic acid, and embryonic exposure

to teratogens such as anticonvulsant drugs, alcohol, organic solvents and cigarettes (Wyszynski

& Beaty, 1996; Peterson-Falzone et al., 2001).

1.1.3 Cleft Lip and Palate Repair

Regardless of their etiology, the majority of cleft lips and palates are surgically repaired within

the first year of life. Specific timing and surgery type is dependent on cleft type, cleft severity,

and the surgeons’ preferences. However, a common pattern is a lip closure around 2-3 months of

6

age and a palatal closure between 6-12 months. This timeline often provides the best balance

between timely closures and ensuring the patient is old enough for surgery (Peterson-Falzone et

al., 2001; Agrawal, 2009). Subsequent surgeries to remove scar tissue from the lip or to graft

bone into an alveolar cleft are done as needed (Kummer, 2008; Tibesar et al., 2009). While

research tends to support a ‘the earlier, the better’ approach to surgery, this may not always be

feasible or desirable (due to situational and other patient-specific factors) and there is a large

spectrum of actual practice (Buckley & Landis, 2009).

1.2 Consequence of Cleft Lip and Palate

1.2.1 Non-speech Consequences of a Cleft

A cleft can result in a large number of consequences for hearing, breathing and eating. Often the

structural anomalies will create airway obstructions and chronic nasal congestion is common

(Kummer, 2008). A cleft can also cause problems for feeding, as it prevents the baby from

achieving adequate force and duration of sucking. Mothers of children with cleft palate may use

special positioning and feeding strategies for their child and there are a number of specialized

nipples and soft squeeze bottles that have been developed to address feeding issues (Amstalden-

Mendes et al., 2007; Breen et al., 2009).

The musculature of the palate is closely tied to the functioning of the Eustachian tubes, which

maintain the equilibrium between external and middle ear air pressure and allow drainage of

fluid (do Amaral et al., 2010). Extensive fluid buildup can lead to the development of chronic

otitis media (middle ear infections) which in turn can result in conductive hearing loss (Handzic-

Cuk et al., 1996; Chen et al., 2008). Since approximately 90% of children with cleft palate are

born with fluid in the middle ear (Peterson-Falzone et al., 2001), and since conductive hearing

loss can have negative consequences for language acquisition (Friel-Patti & Finitzo, 1990;

Jocelyn et al., 1996), this is a crucial problem that must be addressed by the cleft care team

(Kummer, 2008; Carlstrom & Nelson, 2009). Although cleft repair surgery alone often has

limited effects on Eustachian tube dysfunction, it typically resolves on its own around 5-7 years

of age. In addition, the majority of children born with clefts have tympanostomy (eardrum) tubes

inserted in an attempt to lessen any negative effects (Carlstrom & Nelson, 2009; Kwan et al.,

2011).

7

1.2.2 Speech Consequences of a Cleft Palate

1.2.2.1 The Velopharyngeal Mechanism

The velopharyngeal (VP) mechanism is made up of the velum (or soft palate) and the pharyngeal

walls, both lateral and posterior (Figure 5). These three elements work together to seal the

opening located between them: the velopharyngeal port (Moon, 2009; Perry, 2011). Appropriate

opening and closing of this space – known as velopharyngeal valving – connects or disconnects

the nasal and oral cavities from each other. This action is essential for breathing, swallowing and

especially for speech since proper speech is dependent on the rapid and well-timed coupling and

decoupling of these cavities (Peterson-Falzone et al., 2001; Pulkkinen et al., 2001). Interestingly,

the neurological mechanism for non-speech VP closure seems to be distinct from the one used

for closure during speech. Closure during non-speech activities is generally more exaggerated

and firmer than for speech (Kummer, 2008).

Figure 5. The velopharyngeal mechanism, when open (A) and closed (B). [modified from http://quizlet.com/ 6060746/5070-121-test-3-velopfunction-flash-cards/]

The action of velopharyngeal valving is a complex process of muscle interaction. To achieve VP

closure, the velum elevates and elongates in a movement called velar stretch. Simultaneously, the

lateral pharyngeal walls move medially to close against the velum and may even meet at the

midline behind the velum in some individuals. Lateral pharyngeal wall movement can be

asymmetrical, with one side moving more than the other. In some speakers with cleft palate,

even the posterior pharyngeal wall (Passavant’s ridge) contributes to VP closure by moving

forward (Leeper et al., 1998; Kummer, 2008). Although all structures work in coordination, the

relative contributions of each element to VP closure vary across individuals. The three basic

8

patterns of VP closure that have been identified in normal speakers are coronal, circular and

sagittal (Croft et al., 1981) (Figure 6).

Figure 6. The three basic velopharyngeal closure patterns. The black triangles represent the magnitude of contribution of each sphincter component to the closure mechanism. [modified from: Poppelreuter, S., Engelke, W.

& Bruns, T. (2000). Quantitative analysis of the velopharyngeal sphincter function during speech. Cleft-Palate

Craniofacial Journal, 37, 157-165. Figure 4. Reprinted with permission]

1.2.2.2 Velopharyngeal Dysfunction

Velopharyngeal dysfunction (VPD) occurs when the VP port does not close consistently and/or

completely during oral sound production. VPD is categorized by cause: if the prevention of

adequate VP closure is due to a structural defect, this is termed velopharyngeal insufficiency. On

the other hand, if VP closure is inhibited by a physiological disorder that creates inadequate

movement of the VP structures, this is termed velopharyngeal incompetency. Both types of VPD

are common in individuals with a history of cleft palate (Kummer, 2011). The primary aim of a

cleft palate repair is to increase velopharyngeal closure function. Despite a surgeon’s attempts to

restore proper muscle orientation, results are variable. The velum may be too short or the velar

movement may be compromised. Consequently, approximately 20% of individuals will present

with VP insufficiency after repair. An even larger number will have VP incompetency due to the

inability to surgically restore the proper muscle insertions (Kummer, 2008). Several options are

available for improving VP function if the primary surgery is not successful. Secondary surgeries

fall into 2 categories: those that increase the length of the velum and those that decrease the VP

9

space (Peterson-Falzone et al., 2006). A pharyngeal flap surgery, for example, decreases the size

of the VP port by creating a permanent bridge of tissue from the posterior pharyngeal wall to the

velum. This leaves lateral openings which are closed by inward movement of the pharyngeal

walls (Moon, 2009). Some patients may opt for prosthodontic devices such as palatal lifts and

speech bulbs, which aid the patient in achieving VP closure. Despite these options, success is

variable. If the only issue for a patient’s speech is passive nasal air loss, surgery or appliances

may be adequate solutions. However, many individuals also need to eliminate learned, errorful

patterns, such as active productions of nasal air emissions, maladaptive compensatory

articulations and developmental phonological errors (McWilliams et al., 1990; Peterson-Falzone

et al., 2006).

1.2.2.3 Hypernasality and Compensatory Articulations

The severity of VPD is variable. Often, VPD results in hypernasality, where there is abnormal

escape of air (and thus sound) through the nose during the production of oral speech sounds. This

inappropriate coupling of the oral and nasal cavities affects the production of pressure

consonants, such as plosives and fricatives. These sounds require the build-up of adequate

intraoral energy, which the patient cannot achieve given the insufficient VP closure. The

patient’s struggle to produce a greater repertoire of sounds will often lead them to develop active

compensatory articulations. These cleft-type compensatory articulations are characterized by

posterior placement in the vocal tract, since closure behind the VP port allows adequate pressure

build-up (Harding & Grunwell, 1998; Mayo et al., 1998; Searl et al., 1999; Kuehn & Moller,

2000; Peterson-Falzone et al., 2001; Dotevall et al., 2002).

The cleft-type compensatory articulations that an individual develops vary widely as they are

dependent on the unique structural, surgical and situational factors of that individual’s cleft

palate. Common compensatory articulations include palatal, pharyngeal and glottal stops,

pharyngeal and nasal fricatives, and double articulations (where two sounds are produced

simultaneously) (Figures 7 & 8) (Trost, 1981; Harding & Grunwell, 1996; 1998). Consonants are

also often accompanied by audible nasal emissions or nasal turbulence (Sell et al., 1994; 1999;

Kummer, 2008). Approximately 75-97% of patients with a history of cleft palate will have a

speech concern sometime during their treatment (Bardach & Morris, 1990; Witzel, 1991) and

about 40% will have a persistent, even life-long, speech disorder (Stengelhofen, 1989).

10

Figure 7. Placement of common cleft-type compensatory plosives: (A) a midpalatal stop; (B) a pharyngeal stop; (C) a glottal stop. [modified from: Trost, J.E. (1981). Articulatory additions to the classical description of the speech

of persons with cleft palate. Cleft Palate Journal, 18, 193-203. Figure 4. Reprinted with permission.]

Figure 8. Vocal tract configuration during common cleft-type compensatory articulations. (A) the posterior nasal fricative: the tongue creates a constriction at the back of the oral cavity while the velum flutters to produce frication.

(B) a double articulation: the articulation here is of an alveolar and glottal plosive where the air is stopped both at

the alveolar ridge and at the glottis. [modified from: Trost, J.E. (1981). Articulatory additions to the classical

description of the speech of persons with cleft palate. Cleft Palate Journal, 18, 193-203. Figure 4. Reprinted with

permission.]

1.3 The Management of Cleft Lip and Palate Speech Problems

1.3.1 Assessment

Typically, cleft-type compensatory articulations are assessed by a speech-language pathologist in

an auditory-perceptual assessment, and this is the current gold standard for therapy decisions.

Speech samples used to make these decisions often include connected (preferably spontaneous)

speech, specific sampling contexts and stimulability testing (Peterson-Falzone et al., 2006;

Williams et al., 2010). Assessment procedures for cleft palate speech are not standardized

(although there have been some recent efforts: see Henningsson et al., 2008). There are also

11

numerous tools available for the speech pathologist to choose from – for instance, a procedure

popular in the UK is the Great Ormond Street Speech Assessment (GOS.SP.ASS ’98) which

simply documents a patient’s productions (based on auditory perceptions) without assigning any

scores (Sell et al., 1999). Regardless of instrument, any auditory-perceptual assessment relies

solely on the clinician’s ability to perceptually recognize different compensatory articulations.

This approach, however, has several potential pitfalls. Gooch et al. (2001) found that the

reliability of listener transcriptions was low, even for speech pathologists experienced with a

cleft palate population. While previous studies of speech errors have shown that transcription

reliability can be low (mid-60%) for both normal and disordered speakers (Shriberg & Lof,

1991), the listeners in the Gooch et al. (2001) study agreed on only 40% of transcriptions. The

authors outlined several factors that they believe led to these disappointing results, noting that

nasalization and poor intelligibility (common findings in individuals with a history of cleft

palate) negatively influence reliability of listener judgments. Gooch et al. (2001) also discussed

cross-linguistic speech perception research which has shown that listener difficulty with the

discrimination of non-native sounds is increased if the non-native sounds overlap with the

existing phonetic categories of a that listeners’ language (Tess & Werker, 1984; Werker & Tess,

1984; Best & Strange, 1992; Liverly et al., 1993; Flege, 1995). Individuals tend to assimilate the

non-native sounds into their languages’ existing categories (Best et al., 1988; Santelmann et al.,

1999). This effect is relevant for English-speaking individuals with a history of cleft palate since

cleft-type compensatory articulations can be sounds found outside the English language (Trost,

1981; Harding & Grunwell, 1998). It has also been shown that transcriber agreement is lower for

speech samples which contain more than one incorrect sound (Shriberg & Lof, 1991). This could

account for the low transcriber agreement found by Gooch et al. (2001) since individuals with

cleft palate often present with multiple compensatory articulations and have a tendency to

coproduce sounds, a phenomenon known as double articulation (Harding & Grunwell, 1998).

The complexity of cleft-type compensatory articulations makes it difficult to obtain accurate

assessments based on solely auditory-perceptual evaluations (Kent, 1996; Gooch et al., 2001;

Howard & Heselwood, 2002). In this thesis, I argue that speech evaluations of individuals

presenting with these errors would benefit from the inclusion of instrumental speech

assessments. In particular, instruments capable of visually displaying tongue movement and

12

tongue contact information would be well-suited adjuncts to the auditory-perceptual assessments

already utilized by speech pathologists (Trost, 1981; Gooch et al., 2001).

1.3.1.1 An Instrumental Measure: EPG

The instrumental assessment tool that has been most utilized with the cleft palate population is

electropalatography, or EPG. This device uses pseudo-palates to register tongue-palate contact

during speech (Figure 9). Each custom-made palate is molded to fit a participant’s hard palate

and contains an array of electrodes. The pseudo-palate is then connected to a computer which

records each instance that the tongue makes contact with the electrodes (Hardcastle, 1993). The

resulting data take the form of EPG frames, which display the tongue-palate contact location and

timing (Figure 10).

Figure 9. Electropalatography palates from a variety of models: (A) the embedded electrodes; (B) the wires and connector and (C) the positioning within a participants mouth. [modified from: http://rose-medical.com/

linguagraph.html, http://achiralblog.learn-a lesson.com/2008/02/electropalatography.html, and http://utlinguistics.

blogspot. ca/2010_02_01_archive.html]

Figure 10. Single electropalatography frames from a normal speaker for the fricatives /s/ & // and the plosives /t/ & /k/.

13

Research of cleft-type compensatory articulations has benefited greatly from the use of EPG. It

has served to not only support perceptual findings of cleft palate speech (Whitehill et al., 1995,

Gibbon & Crampin, 2001; Gibbon, 2004), but to extend knowledge beyond that which was

accessible in purely auditory-perceptual assessments (Gibbon et al., 2004; Howard, 2004). For

instance, Howard (2004) observed several linguopalatal contact patterns not previously noted in

this population, while Gibbon et al., (2004) were able to bring to light the frequency of double

articulations.

EPG has been used for both the assessment and treatment of cleft-type compensatory

articulations. While its use as a diagnostic tool is relatively well established (Whitehill et al.,

1995; Gibbon, 2004), there is less research on its efficacy as a treatment. Studies have been

restricted due to small participant numbers (Stokes et al., 1996; Whitehill, 1996; Gibbon &

Crampin, 2001; Howard, 2004) or limited inclusion of target sounds (Michi et al., 1993; Gibbon

et al., 2001). Two recent systematic reviews of the literature found no high quality trials from

which to draw conclusions about EPG efficacy as a form of speech therapy for a cleft palate

population (Lee et al., 2009; Kelchner, 2010). Neither review found enough eligible studies to

carry out a proper meta-analysis.

The use of EPG in individuals with cleft palate is limited by fabrication costs and device-specific

factors. The process of creating individualized pseudo-palates is involved, lengthy and quite

expensive. Each palate requires a professional dental impression that is shipped to the fabricator

(located in the UK) and back. Consequently, in some cases (for instance, the Reading model) the

total cost per palate is approximately $600 US (www.articulateinstruments.com). The completed

pseudo-palate may also affect the participants’ normal articulation patterns (McAuliffe et al.,

2008). Most crucially, however, the EPG pseudo-palate extends only as far as the molars.

Therefore, EPG can only provide information about tongue-palate contact that is occurring in the

hard palate region. This is especially important for the cleft palate population since, as discussed

above, cleft-type compensatory articulations are often characterized by posterior placement in

the oral cavity and the pharynx. Thus, EPG investigations of cleft palate speech cannot

characterize some backed articulations due to the limitation of the pseudo-palate. Moreover, data

produced by EPG often represents the end state of a tongue motion. EPG does not display

information about tongue movement before and after tongue-palate contact – information that

may be pertinent to the correct assessment of articulation.

14

1.3.1.2 An Alternative Instrumental Measure: Ultrasound Imaging

I argue that ultrasound imaging may be an attractive alternative to EPG for the assessment of

cleft-type compensatory articulations. Ultrasound requires minimal setup, no individually

manufactured parts and is relatively non-invasive. Beyond the initial purchase of the machine,

ultrasound is not expensive to operate. The ultrasound image is easy to explain and understand,

and is displayed in real time. Furthermore, ultrasound can display the entire tongue length and

shows tongue movement during articulation.

Ultrasound works through the pulse-echo principle where high frequency sound waves are

emitted and received by a piezoelectric crystal located on the ultrasound transducer. These waves

reflect off the tissues they encounter (Sofferman, 2012). The strength of the reflected waves and

the length of time it took the waves to return are both measured. The strength of the reflected

wave is determined by the changes in density of the tissues that are passed through. A strong

signal is reflected if the ultrasound waves pass through tissues that have a large density

difference. Thus, a change from tissue to bone or tissue to air creates a large density difference

and results in a white area on the ultrasound image, while a small density difference (such as

tissue to tissue) results in a darker area (Robinson, 2007). When used for speech recordings, the

frequency of the emitted waves is typically set between 2 and 8 MHz. This creates a favourable

balance between resolution of the image and penetration of the sound waves (Stone, 2005).

Figure 11. A single frame of an ultrasound video, with a sagittal tongue view insert to show the orientation. The curved white line in the ultrasound image corresponds to the tongue surface.

15

For ultrasonographic speech investigations, the transducer is placed under the chin of the

participant. In the Voice and Resonance Laboratory at the University of Toronto, the convention

is to look at ultrasound images in an upside-down orientation. A typical ultrasound image is

displayed in Figure 11.

There are limitations to ultrasound imaging. The placement of the transducer under the chin may

limit mandibular movement during speech and the image provides no stable reference points,

such as the palate or the teeth. Both spatial and temporal resolutions of the ultrasound image can

be limited, and data analysis of the images is not standardized. Additionally, the sublingual

cavity makes capturing an image of the tongue tip difficult. Approximately 1 cm of the tongue

tip is lost in ultrasound imaging – however it has been shown that this is comparable to other

tongue tracking systems such as X-ray microbeam and EMA, in which the first pellet is

positioned about 1 cm from the tongue tip (Stone, 1990; Gick, 2002). While by no means a

perfect tool, the numerous benefits of ultrasound imagining outweigh its limitations and it has a

relatively long history of use in speech research. In the early 1970s, researchers such as Minifie

et al. (1971) and Watkin and Zagzebski (1973) were among the first to explore tongue shape and

displacement using ultrasonographic scans and to compare this ‘new’ tool to the then widely

used videofluoroscopy. Since then, ultrasound has been used extensively to investigate many

other aspects of normal tongue function, such as vowel production (Morrish et al., 1984;

Shawker & Sonies, 1984; Stone et al., 1987; 1988; Chiang et al., 2003) and swallowing

(Shawker et al., 1984; Stone & Shawker, 1986; Sonies et al., 1988; Fuhrmann & Diedrich, 1994;

Chi-Fishman et al., 1998; Peng et al., 2000; Soder & Miller, 2004; Casas et al., 2003; Blissett et

al., 2007). Ultrasonographic investigations of swallowing and speech have also been carried out

with pathological populations, including individuals with cerebral palsy (Kenny et al., 1989;

Sonies & Dalakas, 1991; Casas et al., 1994; 1995), glossectomies (Schliephake et al., 1998;

Bressmann et al., 2005a; 2005b; 2007) and malocclusions (Kikyo et al., 1999; Cheng et al.,

2002; Peng et al., 2003; 2004).

1.3.2 Speech Therapy for Cleft-Type Compensatory Articulations

The speech therapy approach for cleft-type compensatory articulations is motor-phonetic. The

therapy goal is to directly change the movement of the articulators. The clinician begins with

target sound identification and discrimination exercises to ensure the patient is aware of the

16

sound being targeted. Each target sound is then practiced in increasingly complex contexts. After

target stabilization at a monosyllabic level, therapy moves to multisyllabic, word, and sentence

levels. The final goal is carryover of the learned proper articulation into spontaneous speech

(Golding-Kushner, 2001; Bauman-Waengler, 2004; Peterson-Falzone et al., 2006; Ruscello,

2008).

There is a lack of systematic evidence for the efficacy of traditional articulation therapy in

eliminating cleft-type compensatory articulations (Reilly et al., 2004). A study by Van Demark

and Hardin (1986) found that although children with cleft palate improved their articulation

during daily 4 hour articulation therapy sessions for 28 days, the progress was significantly

slower than they had expected. More concerning was that a 9 month follow-up assessment

showed no further improvements compared to the post-intervention assessment, even though the

majority of participants were receiving regular therapy during this time. The only other available

studies of therapy efficacy in this population were conducted with children less than 3 years of

age. Although these children showed an increase in their sound inventory and vocabulary, there

was only limited evidence that the parent-delivered early intervention reduced compensatory

articulation (Scherer & Kaiser, 2007; Scherer et al., 2008).

Speech therapy for individuals with a history of cleft palate is further complicated by two factors.

Firstly, structural abnormalities, such as abnormal palatal shapes or misaligned occlusions, can

influence therapy structure and success. Secondly, as is the case with any speech therapy, the

patient needs to not only learn proper articulation patterns, but also unlearn the improper ones.

Cleft-type compensatory articulations are quite resistant to therapy since they are very effective

for the patient (McWilliams et al., 1990; Gooch et al., 2001). Any failure to completely eliminate

mislearned articulation patterns may lead to the development of double articulations. The

robustness of cleft-type compensatory articulations also means that these individuals are

particularly susceptible to reverting to their old articulation patterns, even if improvements

within the therapy setting are achieved (Golding-Kushner, 2001).

1.3.3 Severity of the Speech Disorder

In a standard articulation test, sounds are scored as correct or incorrect. This provides a good

quantitative measure for the overall severity of an articulation disorder. Assessment of the

overall severity of a speech disorder is important as it can influence many aspects of a therapy

17

program. Decisions about whether intervention is needed, what goals should be set and the

subsequent evaluation of intervention efficacy are all influenced by the severity of the speech

disorder that a participant displays (Gordon-Brannan & Hodson, 2000). A common stand-in for

severity is speech intelligibility, which is calculated by the percentage of words correctly

transcribed within a continuous and spontaneous speech sample (Gordon-Brannan, 1994;

Whitehill, 2002; Wertzner et al., 2007). Unfortunately, speech-pathologists often lack the time to

thoroughly calculate intelligibility and may choose to make a global estimate of speech

intelligibility during clinical assessments. However, these subjective judgments are often

inaccurate (Gordon-Brannan, 1994; Kent et al., 1994). It would be useful for both clinicians and

researchers to have a more realistic way of quantifying the severity of a speech sound distortion.

Ball, Müller and Rutter (2010) argue in their book Phonology for Communication Disorders that

the assessment of severity of a speech sound disorder should form part of any phonological

analysis, and that phonological features or mechanisms should provide an indication of the

degree of articulatory deviation from the target sound. Ball et al. (2010) suggest that clinical

phonology should include a severity metric that can quickly yet quantitatively express this

severity.

“[…] what do we want a clinical phonological analysis to provide us with?

Among the important features must be: […] a metric that allows us to measure

different errors in terms of severity, or deviation from a norm […].” (pp. 205)

The correct vs. incorrect scoring of traditional articulation testing also makes documenting

gradual improvement in speech difficult. As previously discussed, cleft-type compensatory

articulations are both complex and resistant to therapy (Trost, 1981; McWilliams et al., 1990;

Harding & Grunwell, 1996; Gooch et al., 2001). As a result, improvement is often only partial

and incremental, but partial improvement is difficult to capture and quantify. The complexity of

cleft-type compensatory articulations additionally makes assessment based on solely auditory-

perceptual evaluations problematic (Kent, 1996; Gooch et al., 2001; Howard & Heselwood,

2002). Researchers and clinicians would benefit from the inclusion of visual appraisals of the

motor patterns of these errors since these can resolve doubtful auditory-perceptual assessments

(Trost, 1981; Gooch et al., 2001).

18

1.4 Study Objectives and Rationale

In the research discussed in the previous sections, it has been suggested that instrumental

evaluations can be useful supplements to the auditory-perceptual evaluation of cleft palate

speech (e.g., Gibbon, 2004). Ball et al. (2010) also argue that the assessment of disordered

speech could be enhanced through the inclusion of a measure of severity. The research in this

thesis attempted to address these suggestions in two studies.

The studies presented here were explorative and not driven by a strong, falsifiable research

hypothesis. The goal was to create a workable research paradigm and a template for the

documentation of features of cleft palate speech that would allow a fine-grained characterization

of errors. The focus, therefore, was as much on the applicability of the research instrument (i.e.,

ultrasound imaging), as on the characterization of cleft-type compensatory articulations.

I. Exploring Cleft-Type Compensatory Articulations using Ultrasound Imaging

The goal of the first study was to explore the use of ultrasound imaging as a visual supplement to

the standard auditory-perceptual analysis and to add to the current knowledge about cleft-type

compensatory speech errors. The aim was to identify patterns associated with the speech of

individuals with a history of cleft palate. These patterns were used in the following study.

II. Developing and Evaluating a Scoring Metric of Cleft-Type Compensatory Articulations

The results from Study I were used to develop a tentative scoring metric for severity. The main

goal was to create a tool that would allow a comprehensive characterization of both the auditory-

perceptual and the motor aspects of cleft palate speech. The final step involved application of

this scoring tool to the data from a group of patients before and after a course of speech therapy

which consisted of motor-phonetic articulation therapy and visual biofeedback speech therapy.

19

Chapter 2 Study I: Exploring Cleft-Type Compensatory Articulations using

Ultrasound Imaging

2.1 Participants

A total of 13 patients with repaired cleft palate (with or without cleft lip) participated in this

portion of the study. They were assigned invented names as well as numbers. Participants were

heterogeneous with respect to cleft type and had a mean age of 15.1 yrs (SD 8.2). Table 1

outlines important characteristics of the sample.

Table 1. Information about cleft type, age and sex of the participants in Study I.

Participants were recruited from the Hospital for Sick Children and from the Holland Bloorview

Children’s Rehabilitation Hospital, both in Toronto, Canada. Speech pathologists from these

sites identified and referred potential candidates who were then screened by the researchers

20

(which consisted of the author of this thesis, a licensed speech-language pathologist and a

researcher specializing in the application of ultrasound in speech research). Eligible participants

were those over 3 years of age with repaired cleft palate and presenting with multiple active

compensatory articulations. Participants were required to have normal or near-normal hearing

(no more than a mild hearing loss of between 20-40 db HL) and no fixed orthodontic appliances

that interfere with tongue movement. A native or near-native proficiency of Canadian English

was also an inclusion criterion. Data was not available on whether participants were native or

non-native English speakers (i.e. bilingual vs. monolingual). The referring speech-language

pathologists assessed English proficiency prior to referral and participants were again informally

assessed during the intake assessment. Participants were not eligible for this study if they had

any complex craniofacial syndromes or cognitive disabilities. Other participant details, such as

socio-economic status, and surgical or speech therapy invention history, was not collected.

2.2 Methods

2.2.1 Materials

The instruments used consisted of a General Electric Logiq Alpha 100 MP ultrasound scanner,

along with a model E72 6.5 MHz ultrasound transducer with a 114º microconvex array (Figure

12A). The video output from the ultrasound machine was recorded to a digital video camera

(Canon ZR45MC MiniDV Digital Camcorder) with a frame rate of 30 frames per second. The

acoustic signal was recorded simultaneously using an Audio Technica AT4033a Studio

Condenser Microphone. The sample rate was 44.1 kHz and the signal resolution was 16 bit. The

microphone was placed at a distance of about 20 cm from the participant’s face.

Participants were positioned in the Comfortable Head Anchor for Sonographic Examinations

(CHASE 2), a lab-developed apparatus used to stabilize both the participants’ head and the

ultrasound transducer (Figure 12B). This stabilization served to decrease head movement and

create a consistent transducer position, thus reducing between-participant variation associated

with those factors.

21

Figure 12. The ultrasound scanner (A) and Comfortable Head Anchor for Sonographic Examinations (B) used during the assessment protocol.

2.2.2 Data Collection

The task consisted of the isolated production of nonsense vowel-consonant-vowel (VCV)

combinations. This task was chosen because it allowed study of the target sounds in detail. Six

target consonants in 3 different vowel contexts were presented to participants, who were required

to produce 5 repetitions of each combination. All 5 repetitions of each combination were uttered

on a single breath in an approximation of connected speech. The target sounds were the stops []

and [], the fricatives [] and [], and the nasals [] and []. These specific target sounds were

chosen because they are the sounds that individuals with cleft palate often have trouble with, that

is, ones for which compensatory articulations are typical (Trost, 1981, Harding & Grunwell,

1996). They are also visible during ultrasound imaging. The vowel contexts within which these

consonants appeared were [], [] and []. These vowels were chosen as they are common and

are representative of the extremes of the English vowel space. The complete stimuli list is

presented in Table 2.

The stimuli were presented through a Microsoft Office PowerPoint slideshow displayed on a

computer screen in front of the participant. The speech pathologist leading the assessment

modeled each nonsense VCV word prior to the participants’ production of that word. This helped

ensure that the participant was clear on the pronunciation of the target.

22

Table 2. Vowel-consonant-vowel stimuli used.

2.2.3 Data Treatment and Analysis

The resulting digital videos were downloaded from the camcorder to a computer. They were then

segmented using ScreenBlast Movie Studio software. Each final movie clip consisted of video

and audio data for 5 repetitions of a single VCV combination.

The movie clips were reviewed by a team of 3 researchers. This team consisted of the author of

this thesis, a licensed speech-language pathologist and a researcher specializing in the

application of ultrasound in speech research. In collective sessions, these investigators discussed

their auditory-perceptual and visual impressions of each clip. Any incongruity in observations

was discussed until consensus was reached. The agreed-upon qualitative analyses were recorded

in an Excel spreadsheet. This consensus-based assessment approach was used due to the low

inter-judge agreement common in assessments of compensatory articulations (Kent, 1996;

Gooch et al., 2001; Howard & Heselwood, 2002).

Two months after the initial analysis was completed, 12 (5%) of the clips were reanalyzed by the

same 3 researchers. The clips were randomly chosen by a person external to the project and

coded so that the researchers were blinded to participant identity. These new descriptions were

compared to the original ones to determine reliability of listener observations. Each pair of

descriptions was compared on 8 points: 5 auditory-perceptual judgments (1 per repetition), 1

23

nasality judgment, 1 vowel judgment and 1 visual judgment. It was found that there was 91%

agreement between the two points in time, with 75% of the observations being in perfect

agreement, and a further 16% being in partial agreement.

The detailed written descriptions of auditory-perceptual evaluations were used to classify

productions as either correct or incorrect. These frequency counts were used to calculate the

percentage of tokens that were either correctly produced or were errors. The productions

classified as errors were then further broken down into the unique error types that were observed

for each target sound. All error categories that contained less than 5% of the total number of

tokens for a specific target consonant were grouped into an ‘Other’ category. Phenomena that

accompanied productions, such as nasal emissions or clicking, were counted separately. Visual

observations were described separately and compared to the corresponding auditory-perceptual

observations. The covert movements described below refer to tongue gestures that are observable

yet do not have an effect on the acoustic realization of the production which they accompany

(Gibbon, 2004).

2.3 Results

2.3.1 Stops

The productions observed for the target sounds [] and [] are summarized in Tables 3 and 4.

2.3.1.1 Results for the Alveolar Stop []

Overview of Auditory-perceptual Realizations of Productions

Across all 3 vowel contexts, an average of 64% of productions were articulation errors (Table 3).

These consisted mainly of midpalatal stops [] and glottal double articulations. The glottal

double articulations observed were either glottal and alveolar double plosives ([]) or glottal and

midpalatal double plosives ([]). Backing from [t] to [k] and dental realizations of the targets

24

were also seen. The ‘Other’ category consisted of 2 midpalatal affricates. For this target, the []

vowel context produced more errors than either the [u] or [a] vowel contexts.

Table 3. Summary of participant realizations (%) for the alveolar stop target [].

Covert Articulations

Covert lingual gestures were observed for Sabrina (06), who displayed a simultaneous 2-point

elevation of her tongue tip and tongue dorsum during the realization of her [] targets (Figure

13). This inaudible tongue movement was seen across vowel contexts and token repetitions.

Sabrina’s realizations were perceptually typical productions of the alveolar stop, although they

were accompanied by audible nasal emissions.

Within-Participant Variation

Steve (07), Shauna (13) and Sally (14) displayed within-participant variation in their realizations

of []. Steve produced an alveolar plus glottal double articulation [] in the [] and [] vowels,

but a midpalatal plus glottal double articulation [] in the [] context. Shauna realized the target

25

correctly in the [] and [] contexts but produced a midpalatal affricate in the [] context. Sally

demonstrated three distinct realizations of [], one for each of the vowel contexts. Realizations

were consistent for the 5 repetitions of a single VCV combination for all 3 participants.

Figure 13. A frame from the clip of Sabrina’s production of [] showing a 2-point elevation (arrows) during target realization.

2.3.1.2 Results for the Velar Stop []

Overview of Auditory-perceptual Realizations of Productions

An average of 72% of productions for the velar stop target [] were errorful (Table 4). Most

errors were glottal double articulations. This category was divided into 3 types: velar and glottal

double stops [], midpalatal and glottal double stops [], and pharyngeal and glottal double

stops []. Glottal stops [], pharyngeal stops [] and midpalatal stops [] were also observed.

The ‘Other’ category for the velar stop target was relatively large and included midpalatal

fricatives [] and voiced velar stops []. The vowel context that produced the most errors was

[].

26

Table 4. Summary of participant realizations (%) for the velar stop target [].

Covert Articulations

Four participants displayed inaudible tongue movements during their realizations of the []

target. Stella (04) showed simultaneous elevation of her tongue tip and her tongue dorsum in all

3 vowel contexts. Sandra (03), Sabrina (06) and Sylvia (08) displayed accompanying covert

articulations in only 1 of the 3 contexts. Sabrina had consistent elevation of the tongue tip in the

[] context, although her targets were perceptually correct. Sylvia showed pharyngeal excursion

of the back of her tongue during productions in the [] context. Sandra realized all tokens as

glottal stops but was observed to have varied lingual movements across repetitions.

Within-Participant Variation

Seven of the 13 participants showed within-participant variation in their realizations of the velar

stop (see Appendix B for detailed breakdown). Sabrina (06), Shauna (13) and Sally (14)

produced distinct realizations for each of the 3 vowel contexts. They also presented with

variation between realizations of the target sound within a single vowel context. Sandra (03),

Sylvia (08), Sarah (09) and Samuel (11) all had consistent target realizations for 2 vowels, with a

27

different realization for the third. Sandra and Sylvia also showed variation between repetitions of

the target sound within a single vowel context.

2.3.2 Fricatives

The productions observed for the target sounds [] and [] are summarized in Tables 5 and 6.

2.3.2.1 Results for the Alveolar Fricative []

Overview of Auditory-perceptual Realizations of Productions

On average, 83% of productions were errorful for the alveolar fricative target (Table 5). The

errors that were most often observed across all vowel contexts were nasal fricatives [], followed

by dental fricatives [], postalveolar fricatives [], midpalatal fricatives [], and pharyngeal

fricatives []. The ‘Other’ category for this target sound contained instances of voiced alveolar

stops [], and the liquids [] and []. The largest amount of error was produced in the [] context.

Table 5. Summary of participant realizations (%) for the alveolar fricative target [].

28

Covert Articulations

Covert lingual gestures were observed for 5 participants across vowel contexts during their

realizations of []. All 5 participants were observed to have simultaneous elevation of the tongue

tip and the posterior tongue dorsum. In the case of Sandra (03) and Sarah (09), the posterior

tongue gesture was unexpected as their perceptual realizations were produced anteriorly in the

oral cavity. For Stella (04), Sonia (05) and Samuel (11), the opposite was true – their posteriorly

realized productions were accompanied by anterior elevations of the tongue.

Within-Participant Variation

Variation in target production was observed in 2 participants. Shauna (13) produced an [] with

accompanying nasal emissions in the [] and [] context and a mix of dental [] and lateral

fricatives [] in the [] context. Sally (14) presented with variable realizations for all 3 vowel

contexts: she produced both voiced midpalatal stops [] and voiceless midpalatal fricatives [] in

the [] context. In the [] context, her realizations were either correct or voiceless midpalatal

fricatives, and in the [] context, she had either midpalatal fricatives or palatal affricates [].

Sibilant confusion

A common observation for this fricative target sound was sibilant confusion. Six participants

produced acoustically and visually highly identical [] and []. Sonia (05), Sylvia (08), Samuel

(11) and Sally (14) produced nasal fricatives. Steve (07) produced the dental fricative [] with

accompanying nasal emissions. Interestingly, Suzanne (10) showed a gestural differentiation

between the target sounds. Although her [] and [] realizations were perceptually identical

(realized as []), she produced her [] with the tongue tip down and her [] with the tongue tip up.

29

2.3.2.2 Results for the Postalveolar Fricative []

Overview of Auditory-perceptual Realizations of Productions

An average of 56% of tokens were incorrect productions for the fricative [] (Table 6). The most

commonly occurring error was the nasal fricative [], followed by dental [], pharyngeal [] and

midpalatal fricatives [].The largest amount of errors were produced in the [] context.

Table 6. Summary of participant realizations (%) for the postalveolar fricative target [].

Covert Articulations

Inaudible lingual gestures were observed in 4 participants for this target sound. The anteriorly

realized productions seen for Stella (4), Sarah (9) and Shauna (13) were accompanied by

elevations of the posterior tongue. On the other hand, Steve (07), who perceptually presented

with nasal fricatives, had simultaneous elevations of the tongue tip. Although these inaudible

movements were observed across vowel contexts for all participants, they occurred more often in

the [] context.

30

Within-Participant Variation

Three participants demonstrated variation in their realizations of []. Both Steve (07) and Sally

(14) had correct realizations in the [] context, but produced nasal fricatives [] in the [] and []

contexts. Sandra (03) produced a palatal fricative [] in the [] context, a pharyngeal stop [] in

the [] context and had both correct productions and pharyngeal stops in the [] context. As was

outlined in the above [] results section, the more commonly observed pattern for the fricative

targets was sibilant confusion.

2.3.3 Nasals

The productions observed for the target sounds [] and [] are summarized in Tables 7 and 9.

2.3.3.1 Results for the Alveolar Nasal []

Overview of Auditory-perceptual Realizations of Productions

An average of 23% of the tokens across vowel contexts were incorrect productions of [] (Table

7). The errors that were observed included palatal nasals [], rhotacized (or r-like) nasals [] and

velar nasals []. All realizations that fell into the ‘Other’ category for this target sound were

instances of voiced alveolar plosives []. The greatest number of errors was noted in the []

vowel context.

Clicking

Overall, 21% of realizations of the [] target sound were accompanied by palato-alveolar clicks

[] (Table 8). The majority of these instances were noted in the [] vowel context.

31

Table 7. Summary of participant realizations (%) for the alveolar nasal target [].

Table 8. Amount of clicking (%) accompanying the nasal targets [] and [].

Covert Articulations

Covert lingual gestures were not observed for any of the participants during their realizations of

the alveolar nasal [].

Within-Participant Variation

Out of 13 participants, 6 displayed within-participant variation during their realizations of the

alveolar nasal (see Appendix B for detailed breakdown). Of these, Stella (04) and Sarah (09)

32

presented with different realizations of [] per vowel context. Sonia (05), Samuel (11), Sofia

(12) and Sally (14) had consistent realizations for 2 vowel contexts, and a different realization

for the third. Five of these participants also showed variation between repetitions of the target

within the same vowel context.

2.3.3.2 Results for the Velar Nasal []

Overview of Auditory-perceptual Realizations of Productions

The number of incorrect realizations of the velar nasal [] was, on average, 43% (Table 9). The

most frequent errors were palatal nasals [] and alveolar nasals [], followed by pharyngeal

stops [] and alveolar nasal plus glottal double plosives []. Several tokens were categorized as

‘Other’, including voiced velar stops [] and rhotacized (or r-like) nasals [].

Table 9. Summary of participant realizations (%) for the velar nasal target [].

Clicking

Clicking occurred in 16% of realizations for the velar nasal [] (Table 8). These palatal clicks

were observed most often in the [] vowel context.

33

Covert Articulations

Five of the 13 participants presented with inaudible lingual gestures during the production of the

velar nasal. The movement that was observed across participants was the elevation of the

anterior tongue during productions that were realized posteriorly. Both Stella (04) and Sofia (12)

produced a voiced velar stop [] in place of the target while displaying anterior tongue tip

elevation. Stefan (02), Sabrina (06) and Suzanne (10) produced perceptually correct realizations

of the target, yet also presented with simultaneous tongue tip elevation. These covert movements

were observed across vowel contexts.

Within-Participant Variation

Five participants displayed within-participant variation in the articulations they used for the

target [] (see Appendix B for detailed breakdown). Stefan (02) and Sandra (03) produced the

same realization in the context of [] and [] but a different realization in the context of [].

Sonia (05), Shauna (13) and Sally (14) displayed within-participant variation both between

vowel context and between repetitions within the same vowel context. They had different

realizations for each vowel and these realizations were not consistent across repetitions of a

single VCV combination.

2.4 Discussion

2.4.1 Stops

The sounds identified in the combined auditory-perceptual and visual analysis were

predominantly glottal and midpalatal in placement, occurring in both isolation and as double

articulations. This finding is consistent with previous research on common errors of cleft palate

speech (Trost, 1981; McWilliams et al., 1990; Harding & Grunwell, 1996; Kuehn & Moller,

2000; Peterson-Falzone et al., 2001).

The largest error category observed for both stop sounds involved glottal double articulations. It

has been argued that the presence of these errors is indicative of previous speech therapy

34

(Golding-Kushner, 2001). A characteristic articulation error that children with cleft palate will

initially develop is a glottal stop (Harding & Grunwell, 1996). Glottal double articulations

suggest that the patient has acquired a lingual articulation but has yet to eliminate the glottal stop

that was initially developed. The lingual articulation and glottal stop are thus superimposed

(Kummer, 2008). The participants in this study had likely undergone some form of speech

therapy prior to their participation in the study, as is typical for children with a history of cleft

palate of this age range. However, patients were not interviewed about any particulars of their

prior speech therapy.

The covert articulations observed for 5 of the 13 participants may be remnants of perceptually

eliminated articulations, the beginnings of proper target production or idiosyncratic unproductive

gestures. For example, Sabrina (06) had perceptually typical productions of [] yet displayed a

simultaneous unproductive elevation of her tongue dorsum. Gibbon, Ellis and Crampin (2004)

developed several theories for the explanation of covert articulations. First, impaired speech

motor control may be to blame. A child with a history of cleft palate may tend to use ‘whole

tongue’ articulations during speech acquisition and thus may never develop mature lingual

control where the tongue tip and tongue body are able to move independently. The result is that

anterior tongue elevation is coupled with posterior tongue elevation. Second, Gibbon and

colleagues (2004) suggest the concept of ‘lingual assistance’ (first described by Trost in 1981)

where the tongue body is used to aid in the closure of the velopharyngeal port for high-pressure

consonants. Thus, posterior elevation may be attributable to learned ‘lingual assistance.’ The

third and final theory presented by Gibbon et al. (2004) looks at structural abnormalities.

Restricted oral space may limit an individual’s ability to make exact lingual movements. Covert

tongue dorsum elevations may also be compensatory actions, aimed at blocking palatal fistulae.

The between-participant variability that was found was expected. Each participant developed

their own unique set of compensatory articulations depending on their individual structural and

functional challenges. A greater amount of between-participant variation was seen for the velar

plosive [k] – this was illustrated by both the larger number of error categories and the larger

‘Other’ category for this target sound.

It is well documented that normal speakers vary their articulation of a sound depending on the

vowel context (Cheng et al., 2007; Dromey & Sanders, 2009). While these variations can be

35

perceptually noticeable, the sound is nevertheless consistent enough that listeners can correctly

identify it. The individuals within our study showed variation with vowel context. However, their

realizations were not simply slight variations of one sound – they were judged to be producing

distinctly different sounds (variations of both place and manner). As with the between-

participant variation, the between-vowel variation was more prominent for the [] target.

The within-participant variation seen between repetitions of the same vowel-consonant-vowel

combination was an unexpected finding. On what is arguably a simple task – repetitions of a

VCV sequence – some participants produced up to 3 different realizations across the 5

repetitions. This was particularly the case for the [] target sound, with 5 of 13 participants

displaying this phenomenon. While our observations are limited, the results suggest that []

production may be more consistent than [] both across and within contexts. This finding may be

due to the better proprioception (and thus greater awareness and control) of the tongue tip (Crum

& Loiselle, 1972).

The number of errors elicited also varied across vowels for both target sounds. The [] vowel

context elicited the most errors for [] (69%). For [] targets, [] and [] were basically tied for

errorful productions (77% and 80% errors). High front vowels have been shown to increase

perceived nasality and nasalance, which creates more burden on the dysfunctional

velopharyngeal sphincter (Lewis et al., 2000). It has also been argued that this perceived nasality

is increased due to the tendency of cleft palate speakers to articulate [] (and other high front

vowels) with more complete coronal constriction, which blocks oral air flow (Gibbon et al.,

2005). The greater burden placed on the velopharyngeal sphincter may push the patient to

produce more compensatory articulations.

2.4.2 Fricatives

The realizations produced for the targets [] and [] were often errorful: 51-92% of tokens were

classified as compensatory articulations. These articulations mainly differed from the target in

terms of placement but not in terms of manner. The placement of the error was often more

posterior than the placement of the target sound, which was expected based on the previous

36

research (Trost, 1981; McWilliams et al., 1990; Harding & Grunwell, 1996; Kuehn & Moller,

2000; Peterson-Falzone et al., 2001). The compensatory articulations observed were nasal,

midpalatal, pharyngeal and dental fricatives.

A large difference in number of correctly produced tokens was observed. While only 17% of

tokens were correct for the [] target, the [] target had almost half (44%) of its token realized

correctly. This may be accounted for by the more posterior place of articulation for [] which

might have a