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A Choral Conductor's Reference Guide to AcousticChoral Music Measurement: 1885 to PresentBrenda Kaye Scoggins FaulsFlorida State University

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Recommended CitationFauls, Brenda Kaye Scoggins, "A Choral Conductor's Reference Guide to Acoustic Choral Music Measurement: 1885 to Present"(2008). Electronic Theses, Treatises and Dissertations. Paper 4492.

FLORIDA STATE UNIVERSITY

COLLEGE OF MUSIC

A CHORAL CONDUCTOR'S REFERENCE GUIDE

TO ACOUSTIC CHORAL MUSIC MEASUREMENT:

1885 TO 2007

By

BRENDA KAYE SCOGGINS FAULS

A Dissertation submitted to the College of Music

in partial fulfillment of the requirements for the degree of

Doctor of Philosophy

Degree Awarded: Summer, Semester 2008

Copyright 2008 Brenda K. S. Fauls

All Rights Reserved

ii

The members of the committee approve the dissertation of Brenda K. S. Fauls defended on June 23, 2008. ______________________________ Andr Thomas Professor Directing Dissertation

______________________________ Richard Morris Outside Committee Member

______________________________ Judy Bowers Committee Member

______________________________ Kevin Fenton Committee Member The Office of Graduate Studies has verified and approved the above named committee members.

To the Tom's in my life,

I dedicate this document.

One brought back the music,

The other unlocked my heart.

Life has begun anew.

iii

ACKNOWLEDGEMENTS

The path of a doctoral degree is not walked alone. My journey has been blessed with the

guidance and support of a loving family, wise mentors, and wonderful friends - indeed too many

to name. I extend my sincere gratitude to the members of my committee.

First, my deepest gratitude to my major professor, Dr. Andr J. Thomas, whose generous

spirit and navigational fortitude provided for a future of dream fulfillment.

To Dr. Judy Bowers, I extend my thanks for her continued modeling of trailblazing

artistry and fierce dedication to excellence in choral music education.

I would like to thank Dr. Kevin Fenton for his openness and guidance throughout my

degree program.

To Dr. Richard Morris, I extend my appreciation for his continued willingness to bridge

our worlds with the generous sharing of knowledge, resources, and opportunities.

In closing, I thank those who dedicated countless hours, resources, and motivation to the

successful and joyous completion of this personal goal.

iv

TABLE OF CONTENTS

List of Tables ............................................................................................................ vi List of Figures ........................................................................................................... vii Abstract ............................................................................................................ viii 1. INTRODUCTION Purpose of the Study ......................................................................... 1 Need For Study ................................................................................. 1 Delimitations ..................................................................................... 1 Organization of Study ....................................................................... 1 Introduction of Topic ........................................................................ 2 2. SELECTIVE REVIEW OF LITERATURE Choral Blend ..................................................................................... 6 Amplitude ......................................................................................... 7 Formants ~Resonances ..................................................................... 10 Frequency .......................................................................................... 12 Quality of Tone ................................................................................. 17 Registration ....................................................................................... 27 3. HISTORY OF ACOUSTIC CHORAL MUSIC MEASUREMENT 1878-1969 ......................................................................................... 37 1970-1979 ......................................................................................... 44 1980-1989 ......................................................................................... 52 1990-1999 ......................................................................................... 66 2000-Present ..................................................................................... 75 4. SUMMARY ......................................................................................................... 88 5. DISCUSSION AND CONCLUSIONS ................................................................ 93 6. APPENDICES A. Glossary ......................................................................................100 B. Equipment ...................................................................................138 C. Respiratory System .....................................................................153 D. Laryngeal System ........................................................................155 E. Articulatory System .....................................................................157 F. Comparison of Different Interval Naming Systems ....................159 G. Piano Pitch ~ Hertz Chart ...........................................................161 H. IPA English Chart ........................................................................163 7. REFERENCES ....................................................................................................164 8. BIOGRAPHICAL SKETCH ...............................................................................176

v

LIST OF TABLES Table 1. Terminology Correlate Chart............................................................. 3

Table 2. Register Definition by Physiological Activity................................... 30

Table 3. Comparison of the Average Formant Frequencies of Timbre Types to the Average Formant Frequencies of Voice Classifications.......... 49

vi

LIST OF FIGURES

Figure 1. Amplitude Chart................................................................................. 4

Figure 2. Spectrogram of the Vowel /o/ at 131 Hz (C3) ................................... 4

Figure 3. Singing Tasks..................................................................................... 45

Figure 4. Warm-up Cadence ............................................................................. 54

Figure 5. Choral Formations ............................................................................. 74

Figure 6. Chamber Choir Spacings ................................................................... 78

Figure 7. Organization of Choral Formation by Vocal Parts ............................ 82

Figure 8. A Choral Exercise .............................................................................. 83

vii

viii

ABSTRACT

The study of choral sound is accomplished through acoustic choral music measurement.

Physical acoustics are the aspects of sound that can be quantifiably measured and psycho-

acoustics is how we perceive what we hear. This study of choral sound will focus on the

measurable physical acoustic facets of amplitude, frequency and the quality of sound. These

facets of acoustic choral sound have psycho-acoustical correlates of loudness, pitch and timbre.

The success of individual singers within a choral setting is largely dependant upon the

conductor's capacity to identify unconscious vocal habits and provide guidance for their

ameliorated vocal function. A clear understanding of the acoustics of choral sound and the

appropriate application of this knowledge can enable choral conductors to better facilitate the

creation of a superior choral sound. To assist the conductor, appropriate solo and speech

research literature has been included to provide an historical foundation and additional

clarification of apropos subject matter.

An extensive glossary has been provided in this document that codifies terminology from

music acoustics, voice science, choral studies, voice studies, equipment guides and usage,

mathematics, and statistics. The goal of this glossary is to facilitate the intermingling of many

divergent disciplines present in this document and to provide a resource for reference when

reading documents not included in this writing.

The acoustics of choral sound are introduced to provide a unified document in a concise

format that can serve as a springboard for informed practice, rehearsal and study.

CHAPTER ONE

PURPOSE OF THE STUDY The purposes of this study were to provide a concise overview of the history of acoustic choral

music measurement; to provide selective, applicable solo voice measurement studies for a foundational

understanding of subject matter; to provide a detailed glossary of definitions, abbreviations, and

equipment to aid understanding of acoustic choral music literature; and to provide suggested applications

of the findings of acoustic choral music measurement.

NEED FOR STUDY

Acoustic choral music research is wide spread and can be difficult to access both logistically and

physically. The wealth of diverse subject matter with each having its own specific language, equipment,

and procedures makes it difficult to understand and apply to outside settings. The measurement process is

continually changing, diverse and confusing. A concise, thorough reference source is needed to inform

conductors, singers, and students alike.

DELIMITATIONS

The present study excludes two areas of acoustic choral music research: bone conducted sound

and its effect on the singer, and children's choir research.

ORGANIZATION OF STUDY

A review of selected solo voice research articles and empirical choral sound articles are presented

first by subject matter and then historically. The study begins with selected early investigations (1879-

1969) into singing research which have had direct impact on choral research. The subsequent chapters

present sequential researches within each decade up to and including 2007. Following a summary of

research to date, a discussion chapter is devoted to suggested choral applications of research findings for

the choral conductor. The closing section is an equipment reference guide and a detailed, multi-subject

glossary of terms, abbreviations, and procedures.

1

INTRODUCTION OF TOPIC

Choral conductors have the enviable goal of bringing aural life to a composer's work through a

group of individual singers who, once their voices are lifted together, create the choral sound. Consider

Mayer's (1964) words: On occasion, when listening to a fine choir, one hears tone of such infinite beauty

that it is evident that the sum is far greater than the parts; that is, the sound produced is of greater beauty

than would normally be expected from the individual voices involved.1 Is this an occasion made possible

by fate or by luck? No! This greater beauty is the result of an educated, well-informed conductor, who,

while working with and developing exceptional, individual voices, continually strives toward an

amalgamated excellence of such intertwined talents that only one sound is heard a superior choir.

What is required for a choir to be recognized as superior? How does a choral conductor aid the

individual choir singers toward the ultimate choral sound a perfectly blended choir? Most would agree

that vowel unification, diction timing, loudness variance, pitch precision, vibrato amalgamation, timbre

mergence, and choice of registration would be primary considerations. Each of these components is

indigenous to choral sound and equally so, has measurable physical properties which can be examined

within the acoustic study of choral sound.

Acoustics is the study of sound. Acousticians and choral conductors alike are interested in sound

how sound is made, how a produced sound travels, and then how the sound is heard. How sound is

made is the production of the sound. How sound travels is known as the propagation of the sound. How

we interpret what we hear is the perception of sound. 2

What then is choral sound? Is there a way to measure a characteristic of a choral sound? The

answer is yes and the field is known as acoustic choral measurement: the process of determining the

dimensions and/or specifics of the sound of voices singing together. The study of choral sound employs

both physical acoustics and psycho acoustics. Physical acoustics is the reality of sound the aspects of

sound that can be quantifiably measured. Psycho-acoustics is our reaction to sound how we perceive

what we hear. Each time a choir sings forte, is it the same degree of loudness as the previous time they

sang forte? Choral conductors would agree that a choir will produce forte at a level that is in response to

the prior level of sound. Amplitude

1 Mayer, F. (1964). The relations of blend and intonation in the choral art. Music Educator's Journal, 51 (1), 109- 110. 2 Hall, D. (1980). Musical Acoustics: An Introduction. Belmont, CA: Wadsworth Publishing Co. pp. 4-6.

2

is the physical measurement of the choir singing forte. If an acoustician were to measure each occurrence

of forte singing in a song selection, the amplitude would most definitely vary yet the choir, and

conductor, may feel that the fortes were all equal. This is but one difference between what we perceive

(psycho-acoustics) as compared to what we can measure (physical acoustics). This is an example of the

crux of this document. As you can see, for choral conductors and acousticians to understand one another,

an agreement in terminology is crucial. As choral conductors, we describe music with terms that express

our perceptions of music; loudness, pitch, timbre and duration. The correlation of perception terminology

to physical terminology is represented in the chart below. The perceptual component of loudness is

relative to amplitude; pitch to frequency; timbre to the quality of the sound; and duration as it functions in

time.

Table 1: Terminology Correlate Chart

Psycho-acoustics

(Perceptual)

Physical Acoustics Measurement Abbreviation

Loudness Amplitude Decibels dB

Pitch Frequency Hertz

Cycles-per-

second

Kilo-hertz

Hz

cps

kHz

Timbre Quality of Sound Formants,

Formant

Frequencies, and

Resonances

FN or RN

Duration Length of Sound Milliseconds or

Seconds

ms

Sec

Our discussion of acoustic choral measurement is now properly framed for both the choral conductor and

the acoustician.

Frequency is diagramed as the number of sound waves for a given duration of time. The sound

waves' displacement is usually a measurement in Hertz (Hz), for instance A4 is 440 Hz or 440 sound

wave cycles per second (cps). Notice in Figure 1 each cycle is periodic but each has different amplitude

from the baseline.

3

Decibels

x Milliseconds

Figure 1: Amplitude Chart3

All three lines represent a sound that is the same frequency. Listeners would perceive all three sounds as

being the same pitch. Pitch is that which we can discern as being within a continuum of low to high or

high to low. Figure 2 is a spectrogram of a singing sample which shows us both the amplitude and the

frequency of a recorded song sample. Here you will note that the x-axis is in decibels (dB) representing

the amplitude of the sample. The y-axis is in kilo-hertz (kHz) representing the frequency of the singing

sample.

Figure 2: Spectrogram of the Vowel /o/ at 131 Hz (C3)

3 (http://www.acs.appstate.edu/~kms/classes/psy3203/SoundPhysics/amplitude_waves.jpg)

4

Lagefoged explains the quality of sound quite simply: this is the difference between two notes that

are equal in pitch and loudness but have been produced by different instruments, such as a piano and a

violin.4 When choral conductors talk about the differences between voices they will often use descriptors

such as warm, thin, or full. In other words, choral conductors often use the psycho-acoustical term timbre

when talking about the physical acoustic component quality of sound.

The production of human sound requires the interaction of the respiratory system (air), the

laryngeal system (vibrator), and the articulatory system (shaper). The respiratory system provides the

energy air for sound production. The air moves from the lungs into the trachea until reaching the

closed vocal folds (the vibrator of the laryngeal system). Air pressure increases until the vocal folds are

forced apart and caused to vibrate. As the air moves between the vibrating vocal folds, sound is emitted.

This is called the voice source,5 which is a rich spectrum of the harmonics; whole number multiples of the

fundamental frequency. The sound now moves through the vocal tract (the mouth, throat, and nose)6 and

is molded into speech sounds by the articulatory system (the tongue, lips, teeth, and soft palate).

Depending upon the length, shape and degree of mouth opening, these cavities resonate at different

frequencies and shape the sound source into vowels, consonants, and vocal colors that make up the sound

you and I recognize as the human voice. These resonances, also known as formants, are distinct

characteristics of the singer's morphology, training and habitual use of the voice.

The success of individual singers within a choral setting is largely dependant upon the conductor's

capacity to identify unconscious vocal habits and provide guidance for their ameliorated vocal function.

A clear understanding of the acoustics of choral sound and the appropriate application of this knowledge

can enable choral conductors to better facilitate the creation of a superior choral sound. To assist the

conductor, appropriate solo and speech research literature has been included to provide an historical

foundation and additional clarification of apropos subject matter. A conductor's conscious understanding

of the individual's vocal production and its contribution to the synergized acoustical delivery of the

ensemble creates that phenomenon known not only to audiences, but most especially to the creators of

that unique experience that which we know as the choral experience.

4 Ladefoged, P. (1996), 14. 5 Sundberg, J. (1987). The Science of the Singing Voice. Northern Illinois University Press: Dekalb, Illinois, p. 49. 6 Lagefoged, (1996), 92.

5

CHAPTER TWO

REVIEW OF LITERATURE

Choral Blend The joining of individual voices to create a combined sound, a choir, requires choral blend. When

one voice is heard above all others, choral blend is adversely affected. Cashmore (1964) points out that

an individual's attempt to lead his or her vocal section is both vocally taxing and is a detriment to the

growth of independent singers.7 Often though, an individual may have a larger voice than their fellow

choir members. Voice instructors often have issue with conductors who ask such singers to sing with a

minimized production in order for the choir to achieve an overall choral blend.

To achieve this perfect choral blend, Mayer8 believed the focus needed to be on timbre, dynamics

and pitch. Vibrato and the tuning accuracy of singers have great impact on the choir's overall intonation.

His method for improving choir intonation involved both just and non-tempered tuning and began by

tuning perfect octaves on the pitches of D4 and/or E4. Meyer would start with the bass section and then

add each vocal section, one at a time at a mf level, until all of the singers were participating. Once the

octaves were in tune, Meyer would move into perfect fourths and fifths, again centered on D4, and would

remain there until the intervals were mastered. Moving gradually through this process, his choir was able

to master intonation and thereby achieve a more perfect choral blend.9 This empirical approach is used

by many fine conductors.

F. Melius Christiansen and Weston Noble are recognized as two important American conductors

of the twentieth century. Giardiniere, in his 1991 dissertation, explained Weston Nobles re-definition of

F. Melius Christiansens concept of voice matching to achieve choral blend. Christiansen directed singers

to alter their sound to match the person(s) next to them, whereas Noble positioned singers next to other

singers whose vocal character was similar. Noble believed an acoustic phenomenon would occur when

voices were placed correctly. Recordings of Nobles voice matching procedures of two to seven singers

were compiled into a cassette perception survey and then was mailed to active choral musicians (N =

218). Auditors showed marked preference for Nobles final arrangement of voices in more than half of

the listening survey. Auditors were not consistent in responses which had only two voices (duets). This

7 Cashmore, D. (1964). A good performance. The Musical Times, 105 (1451), 56-57. 8 Mayer, F. (1964), 109-110. 9 Ibid.

6

study had many responses concerning the quality of the recordings, the process of mailing the tapes, the

varying quality of the listening equipment, and its effect on listener preference.10

Amplitude

Amplitude is the measurable physical attribute of what is perceived as loudness. Specifically,

amplitude is the extent of the variation in air pressure from normal air pressure. When air pressure

reduces, the sound is perceived as less loud and conversely, when the air pressure increases, the sound is

perceived as louder. However, how much air pressure increases or decreases is not equal to how much

louder or softer the sound is perceived.11 When measuring the sound pressure level (SPL) of a vowel

sound, the amplitude of the voice source is the sound produced by the vocal fold vibrations. The main

controlling element for this amplitude is subglottal pressure. Other elements involved are the relationship

between the resonances' frequencies of the vocal tract and the partials present in the spectrum. When air

pressure increases, the amplitude increases and conversely when air pressure decreases the amplitude

decreases. Gramming (1991) designed the following experiments to study the effect of loud and soft

phonation on the spectral envelope.

In the first experiment, a female participant was recorded speaking the vowel /a/ at approximately

400 Hz, first in soft phonation and then in loud phonation. The loud phonation revealed all 12 partials

below five kHz. However, in soft phonation, only the first two partials were present and the F0 (fundamental frequency) was stronger. The F0 (fundamental frequency) is the number of repeating cycles

of the vocal folds in one second and is measured in Hertz (Hz). The first partial of a sound is also called

the F0 (fundamental frequency). A partial of the sound is a component of a complex sound which can be

the F0 (fundamental frequency), a harmonic of the F0 (fundamental frequency), or an overtone of the F0

(fundamental frequency). This single participant pilot study was utilized as a basis for the next study.

Participants (N = 20, n = 10 women and n = 10 men, all with normal, untrained voices) were recorded

speaking the vowel /a/ in soft and loud phonation. Overall, the F0 (fundamental frequency) remained

louder than the partials in all participants' soft phonation. However, in loud phonation, a partial, which

represented an overtone, was the loudest. An observed consistency occurred when the resonances

frequencies remained the same although the F0 (fundamental frequency) increased, in loud phonation, the

strongest partial in the spectrum correlated with the first resonant frequency. Again, as in the pilot study, 10 Giardiniere, D. (1991). Voice matching: an investigation of vocal matches, their effect on choral sound and procedures of inquiry conducted by Weston Noble (Doctoral dissertation, New York University, 1991). UMI ProQuest Digital Dissertation Abstracts, 241, AAT 9213181. 11 Lagefoged, P. (1996), 14-16.

7

the louder phonations had many more partials than the softer phonations. The increases were evident

when the F0 (fundamental frequency) was at a lower pitch, as in the male participants.

Participants (N = 22 speech therapy students) in the second experiment were recorded speaking

the vowels /a/, /i/, and /u/. The averaged phonetogram results showed the vowel /a/ was ~10 dB higher in

sound pressure level (SPL) than /i/ or /u/ when the participant sounded a low F0 (fundamental frequency).

As the F0 (fundamental frequency) rose, the sound pressure level (SPL) differences between the vowels

reduced. In loud phonation, the sound pressure level (SPL) increased as the frequency of the first formant

increased. In soft phonation, there was no difference between the vowels because the F0 (fundamental

frequency) was the strongest partial.

Grammings' third study utilized both healthy (N = 20 men and women) and non-healthy (N = 10

female patients diagnosed with non-organic dysphonia) participants. Again, phonetograms were made of

the vowel /a/ on a pitch chosen by the participant. The pitch chosen by the participant was evaluated and

described in relation to the participant's full range. The goal of this study was the short term variance in

sound pressure level (SPL) in loud and soft phonation. The patient participants, who used soft phonation,

more than 60% of the time, chose a frequency in the higher part of their range which showed significantly

more sound pressure level (SPL) variation. The resulting sound pressure level (SPL) variation mean for

loud phonation was 2 dB whereas in soft phonation the sound pressure level (SPL) variation mean was 5

dB which led Gramming to conclude voice control was more difficult when the patient participants used

soft phonation.

Weber (1992) was interested in the difference between vibrato and straight tone singing on sound

pressure level (SPL). College choir sopranos (N = 20) were recorded singing /a/ for representative low,

middle, and high pitches in loud and soft dynamics with both vibrato and straight tone. For each

participant, this resulted in 24 trials per soprano (each condition was repeated). Analysis of the recordings

found no significant difference in sound pressure level (SPL) for any condition except for a slight

difference in the loud vibrato condition. Weber concluded conductors should determine the use of

straight tone or vibrato be based on the acoustic characteristics of the performance location since the

sound pressure level (SPL) showed very little variance.12

Sundberg et al. (1998) chose an unexplored musician population to investigate voice source

characteristics, one of which was intensity. Singing participants (N =6 premier male country singers) 12 Weber, S. T. (1992). An investigation of intensity differences between vibrato and straight tone singing (Doctoral Dissertation, Arizona State University, 1992). ProQuest Dissertation Abstracts International, AAT 9223155.

8

wore a Rothenberg mask and were recorded speaking and singing the CV (consonant-vowel orientated)

syllable /pae/. The speech condition was two fold: in speech condition one, the participants started at

basal pitch (lowest comfortable pitch) and repeated /pae/ in soft, medium, and loud voice. This pattern

was repeated at four successive thirds, imitating in speech the pitch pattern of an arpeggio. In the second

speech condition, the participants spoke the syllable /pae/ to the pattern of a limerick in soft, medium and

loud voice.

The singing conditions were also two fold. The participants chose and sang a song from their

country repertoire on a starting pitch of their choice without accompaniment. The participant was

encouraged to sing with all the same inflections, dynamics, and intensity as in a performance. The second

singing condition had the participants sing The National Anthem at a starting pitch of their choice.

Extensive detail was given to the recording and analysis process including the equipment used.

Listening participants (N = 19 singing experts) listened to a perception test designed to answer the

question How much pressedness do you hear in this voice? Answers were given on a 100-mm visual

analog scale which ranged from None to Extreme. One third of the samples were replayed to test for

reliability. Listening participants perceptions included an awareness of different voice quality between

the chosen country song and The National Anthem. The participants reported that the amount of

pressedness heard in the samples increased with higher pitches that were coupled with louder volume.

The correlation between the pressedness of the voice on higher pitches with increases in sound

pressure level (SPL), which would be expected to also double the subglottal pressure (Ps), was not evident

in the results. The results suggested that the smaller the sound pressure level (SPL) gain, the greater the

perceived pressedness. But, as expected by the authors, the closed quotient (CQ) and the glottal

compliance were greater in loud speech than in soft speech whereas in singing, the participants used

similar or slightly higher closed quotient (CQ) values. The authors concluded that a voice source

characteristic of country singing was very high closed quotient (CQ) values in loud singing. This

characteristic, often considered a cause of vocal damage (pressedness), had not manifested itself in the

vocal fold pathology of these participants.13

Miller, Schutte and Doing (2001) explored soft phonation in professional tenors. Participants (N =

2) were fitted with an electoglottograph collar and an esophageal balloon while singing into a microphone

four vocal tasks: 1) a sustained Ab4, 2) an Ab4 arpeggio, 3) a sustained note in falsetto, and 4) a sustained 13 Sundberg, J., Cleveland, T., Stone, R., & Iwarsson, J. (1999). Voice source characteristics in six premier country singers. Journal of Voice, 13 (2), 168-183.

9

note in modal production. Each vocal task was performed in a soft level and then in a medium level

gradually down to a very soft level while maintaining the same vocal production. One participants vocal

timbre was described as lyrical while the other voice was described as robust. The lyric tenor had no

difficulty with the requested tasks. The robust tenor experienced a moment of silence as the voice would

equalize from a louder production to a softer production. This was accredited to a longer closed quotient

(CQ) phase that was incomplete and a steeper slope on the electroglottography (EEG) that became

significantly shallower in the very soft level. The lyric tenor maintained a steady subglottal pressure (Ps)

throughout the entire task. This data prompted the authors to suggest that messo di voce is a voice

register, not a vocal task.14

Formants ~ Resonances

Pulsating air flow through the glottis (the space between open vocal folds) is known as the voice

source. When sound is measured at the voice source, the fundamental frequency (F0) will have the

greatest amplitude. Each cavity of the vocal tract will have a resonance that will be represented in the

source spectrum envelope as peaks of amplitude at various frequencies. These peaks of amplitude are

formants. Beginning with the first spectral peak occurring at the lowest frequency, the formants are

labeled in order F1, F2, F3and so on. Each formant rises in frequency.15 The resonance frequencies

change as the vocal tract molds articulation. Specific frequencies increase with individual vowels that are

articulated in a specific region of the articulatory system. The first frequency peak (F1) is usually

associated with the pharyngeal space (back cavity of the mouth) particularly with the vowels /e/, /i/, and

//. The second frequency peak (F2) is generated in the front cavity of the mouth for the back vowels /u/,

/o/, and //. The third frequency peak (F3) is dependant upon the front of the tongue, especially in vowels

/u/, /o/, /i/ and //. The fourth and fifth frequency peaks again have front of the tongue influence on the

//, //, and /e/ whereas the back of the tongue influences /u/, /o/, and /i/. The fifth peak is strongly

impacted by the larynx tube.16 It is the unique morphology of each singer that requires individually

specific training to achieve maximum resonances from the vocal tract. Knowledge of the production and

14 Miller, D. G., Schutte, H. K., Doing, J. (2001). Soft phonation in the male singing voice: preliminary study. Journal of Voice, 15 (4), 483-491. 15 Fant, G. (1970). Acoustic Theory of Speech Production: With Calculations Based on X-ray Studies of Russian Articulations. Mouton: The Hague, pp. 17-20. 16 Fant, (1970). 121-122.

10

propagation of these resonances will aid in developing voices that are capable of singing healthily over

orchestras and in producing full rich choral ensembles.

One of the most cited articles in voice research is Fant et al.'s (1972) article on the measurement of

subglottal formants. Measurements were taken of the first through third formants (F1, F2, and F3) of the

recordings of participants' speaking the CV (consonant-vowel) syllable /pa/. Results of this study

suggested the glottal strength of participants had a direct impact on the measurement of subglottal

formants. Weak and/or breathy voices showed more subglottal formant traces than those of normal

voices. Formant measurement data garnered in this study was used to develop computer models of

synthesized voices.17

Miller and Schutte (1990) defined formant tuning as using vowel modification to approximate one

or both of the two lowest resonances of the vocal tract to harmonics of the glottal source.18 A leading

Netherlands opera baritone was recorded singing melodic patterns on a variety of vowels and CV

nonsense syllables with a catheter (fitted with a miniature wide band pressure transducer) inserted through

the neck and into the glottis area as well as an EGG (electraglottographic) neck band. Vocal production

began once the topical anesthesia had faded. Supra- and sub-glottal pressures were measured and well as

the formant frequencies and harmonics. Phonations were made at the participants choice of pitch and

ranged from 230 Hz to 380 Hz (Bb 3 to F4) an area where vocal tract realignment is usually needed to

move baritones into full head voice. In other words, the participant reduced the sub-glottal pressure (Ps)

and modified the vowel to make a smooth transition into head voice.19

Miller and Schutte (1992) continued their research into subglottal pressure and formant

measurement by recording professional male singers (n = 2), equipped with two glottis transducers, an

electoglottograph (EGG), and a microphone at a distance of 30 centimeters. The recorded singing tasks

were four scales on the vowel /a/ and sustained /a/ vowels on four range- representative pitches.

Conclusions included confirmation of measurement tools to show center frequencies of pitches when

vibrato was present in the singers' vocal production. The same equipment was able to accurately measure

17 Fant, G., Ishizaka, K., Lindqvist-Gauffin, J., Sundberg, J. (1972). Subglottal formants. STL-QPSR, 13 (1), 001-012. 18 Miller, G., Schutte, H. K. (1990). Formant tuning in a professional baritone. Journal of Voice, 4 (3), 231. 19 Ibid.

11

the frequency distance between harmonics and a dominant formant. The vocal tract configuration was

confirmed, in this study, as a variable in determining formant frequency modulation.20

Ternstrm (2007) chose to investigate formant frequencies by using a professional barbershop

quartet. Three four-track recordings of Paper Moon were sung by the participants in an absorbent room.

The recordings included the participants singing together but with each singer placed in one of the four

corners of the room, each participant singing alone, each participant speaking alone, and then all

participants speaking together. Each singer wore a small microphone taped on the end of his nose. The

recordings were analyzed through inverse filtering utilizing Decap software to determine the identity of

formant frequencies, the measurements of the spread of formant frequencies, and the relationship of

partials in both individual and ensemble measurements. The vowels chosen for analyzing were /u/ (to), /i/

(be), and /a/ (divine).

Results suggested singers separated their formants from each other as evidenced in wide- spread

formant frequencies. Formant frequencies were often on or close to a partial of the individual singer as

well as to the common partials of another singer. The spread formant frequencies may have been in an

effort to hear oneself better so that the combined sound might have seemed larger and more expanded, in

other words, more resonant. In the barbershop world this is referred to as locked and rung!21 Success for

this quartet was achieved through varied vowel production versus attempting to sing exactly the same

vowel the opposite of choral singing. Barbershop quartets may be able to increase their resonance by

adjusting their vowel quality.22

Frequency

Frequency is the rate of vibration of a periodic event. In phonated sound this means the number of

sound wave cycles per second (cps). When we measure frequency it is expressed in hertz (Hz). We

assign a specific name to a pitch because we do not hear frequencies. Our available hearing range of

frequency is approximately 20 Hz to 20,000 Hz.23 The lowest note that we can hear is what would be the

lowest C (Csub zero) on the piano if it were extended two whole tones. Each successive C going from left to

20 Schutte, H., Miller, D., Svec, J. G. (1995). Measurement of formant frequencies and bandwidths in singing. Journal of Voice, 9 (3), 290-296. 21 Ternstrm, S., & Kalin, G. (2007). Formant frequency adjustment in barbershop quartet singing. International Congress on Acoustics, Madrid, September 2007, 1-6. 22 Ibid. 23 Lagefoged, (1996), 21.

12

right on the piano is ordered numerically C1, C2 and so on. These notes are said to be an octave apart.

C4 is commonly referred to as middle C. A4 is the fourth A on the piano from right to left and is

commonly known as A440 because the vibration of the air stream as it passes through the glottis is 440

cycles per second (cps) or 440 Hz. When we speak of pitch, we are using a perceptual term of relativity

that functions on a scale from low to high. When we speak of frequency, we are speaking in absolutes

using a term of measurement of the number of sound waves occurring within a second. (See Appendix D).

In 1979, Shipp et al. recorded participants (N is not provided, n = 10 professional operatic singers,

n = not provided number of spastic dysphonic patients) singing a variety of sustained vocal lines utilizing

targeted frequencies throughout their ranges. Acoustic analysis revealed many differences between the

sub-groups. The singer participants' variance of vibrato pitch was within 0.5 semitones whereas the

patient participants had very little vibrato as reflected in their signal amplitude. The patient participants

had very large cycle-to-cycle variations whereas the singer participants' variations were very small.

However, the variation mean rate of vibrato was similar for both the singers and the patients. The results

suggested the physiological manifestation of vocal tremor and vibrato are similar, yet, singers may have

mastered a stabilizing technique in which the nerve pulses of muscles are inhibited except for the superior

laryngeal nerve which stimulates the cricothyroid muscle. Perhaps patients and less experienced singers

allow, or do not suppress, stimulation of muscle nerves in areas of the vocal tract (including the

respiratory system) that cause muscles to engage that are not needed for phonation.24

The next three landmark studies investigated the understanding of singers' vowel production in a

variety of singer modes of phonation. Bloothooft and Plomp (1984) first recorded each singer (N = 14

professional singers, n = 7 male and n = 7 female) in an anechoic room singing the nine Dutch vowels for

one to two seconds in each of the following tone qualities: neutral, light, dark, free, pressed, soft, loud,

straight, and extra vibrato. These terms were taken from accepted vocal pedagogy and the participants

confirmed knowledge of and an understanding of each of the terms. Comparison of the nine modes'

average sound pressure level (SPL) revealed that the neutral mode and the free mode appeared to be

interchangeable descriptors of the same mode of singing. Comparison of the nine modes spectral

compositions showed that the presence of, or increased use of vibrato did not vary the spectral

24 Shipp, T. & Izdebski, K. (1979). Elements of frequency and amplitude modulation in the trained and pathologic voice. Acoustical Society of America Supplement, 1 (66), Fall 1979, 56.

13

compositions. From these conclusions, Bloothooft and Plomp reduced the number of modes to six; soft,

light, dark, neutral, pressed and loud.

Each singers classification was used to determine the fundamental frequencies (F0) used for each

participant (five for men and four for women). The sopranos and tenors showed twice the spectral

variance in the F0 (fundamental frequency) across the vowels and modes of singing as that of the bass and

alto participants. Although no perceptual data were taken, authors suggested sopranos and tenors needed

better intelligibility of vowels. The greatest vowel variance for all the participants was the vowel /u/. The

vowels /a/, / /, and // showed half of the variance than that of the vowel /u/. The information was not

provided regarding measurement tools used for the vowel variances; however, great detail was given to

the measurement process and results.25

Bloothooft and Plomp's (1985) second article used the same subjects and data to discuss the vowel

spectrum for each participant with respect to the main effect of the four vowels. Each vowel was

measured in dBs and at increments of ten milliseconds with a 1/3-octave band filter spectrum that was

normalized for SPL (sound pressure level). A comparison was made between the perception-oriented

spectrum space (formant frequencies) and the production-oriented spectrum space (from 1/3 octave

spectra). The vowels were represented as the most important single source of spectra variance for low

fundamental frequencies (F0). Male and female variants were consistent with one another. The

relationship between the average sound level of the singers formant (Fs) and the fundamental frequency

(F0) was found to be vowel dependant. When the fundamental frequency (F0) was higher than 392 Hz, the

results showed a lower singers formant for women. The modal register had less variability in the first

formant (F1) than the falsetto register and it was hypothesized that in singing higher frequencies, the first

formant (F1) is very close to the fundamental frequency (F0). Bloothooft references Sundberg's (1981)

results which showed strong acoustic coupling between glottis and vocal tract26 and suggested this was a

possible cause for these results.27

25 Bloothooft, G., Plomp, R. (1984). Spectral analysis of sung vowels: I. variation due to differences between vowels, singers, and modes of singing. Journal of the Acoustical Society of America, 75 (4), 1259-1264. 26 Sundberg, J. (1981). Formants and fundamental frequency control in singing. An experimental study of coupling between vocal tract and voice source. Acustica, 49, 47-54. 27 Bloothooft, G., Plomp, R. (1985). Spectral analysis of sung vowels. II. The effect of Fundamental frequency on vowel spectra. Journal of the Acoustical Society of America, 77 (4), 1580-1588.

14

Again, the same data is used in Bloothooft and Plomp's third study, which compared the individual

participant's spectra of the different modes of phonation. The overall conclusions confirmed that primary

differences in the fundamental frequency (F0) were associated with the differing lengths of the male vocal

tract whereas in the women, the main difference was associated with the glottal opening. The pressed-

dark mode of singing in the participants clearly showed increased pharyngeal volume which was directly

influenced by the height of the larynx.28

Maxwell (1985) investigated the effect of masking on a singer's ability to sing in tune. Masking is

the obscuring of one sound by another. In singing, the inability to hear oneself sing is often the result of a

masking noise which sometimes is the loudness of the surrounding singers. The greatest masking effect

within a choir occurs within one's own vocal section, for those singers are singing the same frequencies

(what we think of as pitches).

In the first of three experiments, participants (N = 24 college voice majors) were recorded singing

vocalizes and song excerpts with and without masking noise. The second experiment recorded

participants (N = 15) as they sang The Star Spangled Banner in a key of their choosing in which

masking noise was added at an unknown, random point. The third experiment was a 10-week

longitudinal study with four treatment conditions: 1) normal lessons and normal practice (CG control

group); 2) white noise lessons and normal practice; 3) normal lessons and white noise practice; and 4)

white noise lessons with white noise practice. In each study, pre-experiment and post-experiment

recordings were made of each participant prior to and after each experiment. From these recordings of the

first two experiments, a listening tape was made for judge participants (N = 9, n = 3 voice teachers, n =

professional non-voice musicians, and n = 3 lay musicians). The listening tape contained excerpts from

the pre- and post-recordings of participants. The judges ranked the voice quality of the first excerpt as

compared to the voice quality of the second excerpt as better, same, or worse (studies one and two). This

same procedure was executed for an intonation comparison of the paired excerpts. For the third

experiment, the judge participants were asked to rank the singer participants' vocal progress between the

first of the paired excerpts as compared to the second of the paired excerpt. Five options were provided

for the ranking: great progress, considerable progress, some progress, same, and worse.

The judges perceptions of the first experiment participants samples found white noise adversely

affected participant intonation and voice quality. It was not surprising that the judges were able to detect

28 Bloothooft, G., Plomp, R. (1986). Spectral analysis of sung vowels III. Characteristics of singers and modes of singing. Journal of the Acoustical Society of America, 79 (3), 852-864.

15

the point when masking noise had been introduced in the second study. The sample group of the third

study, which received the highest mean score ranking, had masking noise during their lessons and practice

time. However, comparison of variance within groups found much greater variance within all other

groups outside the control group. Teacher guidance with white noise indeed produced greater results.

Participants without teacher guidance of white noise regressed. In all studies, participants tended to flat

ascending passages, sharp descending passages, sharp sustained notes, and modify / / to // or /a/ when

masking was introduced. The recording, editing, and playback equipment are unknown for the listening

participants' perception listening tape. Also, the production of white noise is unknown. These specifics

would aide in understanding the conclusions drawn, the perceptions of the auditors, and would provide a

roadmap from which to apply the information garnered. However, great detail is given to the statistical

analyses of the listening participants responses.29

Gramming et al. (1988) wondered what the relationship was between the changes in voice pitch

when loudness was considered as a factor. Male and female singers and non-singers (N = 20) were

recorded singing triads (singers) and pitch glides (non-singers) to provide data for phonetograms. The

same participants were asked to read a lengthy (non-related) passage, first in a quiet environment,

followed by three additional readings in steadily increasing noisy environments. Singers were found to

use a stronger fundamental frequency (F0) and an elevated frequency with increased noise in the

environment. Non-singers showed no difference in pitch. Authors proposed singers wider pitch range

accessibility and familiarity with their full pitch range as an explanation for these results. Additionally,

this may be a reason for reduced pathology in similar life settings.30

Nordmark and Ternstrm (1996) looked at intonation from a very different angle. The most

defining interval of Western tuning systems (Pythagorean, pure, and equal temperament) is the major and

the minor third. Hemholtz believed that intervals which were not "purely" tuned caused a "beating" which

would be heard as a dissonance.31 Nordmark and Ternstrm created synthesized non-beating ensembles

sounds to add to the existing knowledge of beat ensemble sounds and their relationship to intonation. To

create these sounds, synthesized violas were used because they most closely resembled human sounds -

once a flutter component was added. The average ensemble flutter level was found to be between 10-15 29 Maxwell, D. (1986). The effect of white noise masking on singers. Journal of Research in Singing, 8 (2), 9-19. 30 Gramming, P., Sundberg, J., Ternstrm, S. Leanderson, R., Perkins, W. H. (1988). The relationship between changes in voice and pitch loudness. Journal of Voice, 2 (2), 118-126. 31 Hemholtz, (1885), 24.

16

cents (Ternstrm, 1993).32 For this experiment, nine cents of flutter was added to the synthesized viola

sounds. Two groups of three ensemble sounds were used to create versions of major thirds: the first

group had the fundamental frequency (F0) set at 220 Hz; the second group was set at 390 cents above the

fundamental frequency (F0) for a slightly larger major third interval than a pure major third which would

have been at 386 cents above the fundamental frequency (F0). Once created, the dyad was replicated 9

more times at different fundamental (F0) pitches. Each dyad was repeated twice in random order on a 20

dyad perception test. The headphoned listening participants (N = 16, n = 11 undergraduate choral music

education students, and n = 5 orchestra musicians) were given the opportunity to tune each dyad to their

preference for a major third. The range of cents above the fundamental was 350 to 450 cents. If a

participant expressed preference for a deviation above or below this range, the computer would not allow

the participant to move on to the next dyad. The results showed listener preference for interval size of a

major third was 395.4 cents - which is closer to equal temperament than to pure intonation (386 cents).

Participant results suggested that non-beating intervals (pure intonation) are not preferred. However,

participant preference reliability was inconsistent in this study.33

Quality of Tone

Helmholtz (1885) described the quality of a tone as being sometimes called its color, timbre, or

register.34 When one is able to discern one pitch of the same frequency, duration, and loudness from

another it is because its quality of sound is different from the others. Hemholtz determined that the

difference must be in the manner in which the motion is performed within the period of each single

vibration.35 This manner can be perceived as brighter or more acute; it could be the way the tone begins

(onset) or ends (off set); the amount of resonance (or the lack of resonance) in the sound; or the effect of

one's pronunciation on the tone.36 Fillebrown believed the quality of a tone was the result of the singer's

mood or emotion; an expression of the individual which was completely unique to the singer.37

32 Ternstrm, (1993), 7. 33 Nordmark, J. & Ternstrm, S. (1996). Intonation preferences for major thirds with non-beating ensemble sounds. TMH-QPSR, 37 (1), 57-62. 34 Helmholtz, (1885), 24. 35 Ibid., 19. 36 Ibid. pp. 65, 66, 113. 37 Fillebrown, (1911), 7-8.

17

Fillebrown did not have a scientific, anatomical, physiological explanation for the quality of a singer's

tone but believed the answer would be found through continued research.

Schoen (1921), a student of Carl Seashore, studied the presence of vibrato in professional

sopranos (N = 5). Professional recordings of Nellie Melba, Alma Gluck, Frances Alda, Emma Eames,

and Emma Destinn singing Bach-Gounod's Ave Maria were analyzed by tonoscope (early stroboscopy).

The selected pitch was the third note of the composition, D5 (~ 587.33 Hz). Each participant's sample

was analyzed with respect to the attack of the note, the accuracy of intonation, the fluctuation of the

frequency, the release of the note, and the tonal movements leading to the note and away from the note.

Individual characteristics were provided for each participant. The overall conclusions showed this tone

was led to from a lower note and resulted in a low attach frequency. Schoen surmised a time interval

might have elapsed before the intensity of breath was engaged fully. Equally interesting was that the

release of the note was high in frequency even though the next note was lower. Schoen conjectured that

this might be due to an attempt to maintain a steady pitch to the end of the tone and that breath support

might wane, causing the participant to press more breath support which raised the pitch. Each time the

same pitch from the same musical phrase was repeated, the participant sang it differently. The vowel

quality seemed to have no effect on the pitch accuracy. Movement from tone to tone seemed to be glide-

like, almost a portamento. The participants seemed to sing sharp with respect to both pure and tempered

intonation. Schoen concluded [erroneously] that although vibrato was present in every voice, it was only

present when there was strain in the accompanying muscles. Schoen suggested the muscle strain was in

response to the singer's emotional excitement while singing and that vibrato was the result of a neuro-

muscular condition characteristic of the singing mechanism and therefore a periodic-pitch phenomenon.38

Bartholomew (1934) hypothesized that oscillator recordings of singers, both professional and

amateur, would reveal the physiological structure(s) responsible for various qualities. With this

information, singers, as much as was possible, would be able to consciously control the voice mechanism.

Bartholomew recorded 46 films and from them defined four characteristics of good male voice quality:

vibrato, tonal intensity, the presence of a strengthened low partial at 500 cycles per second (cps) or lower,

and the presence of a high formant lying between 2400 and 3200 cycles per second (cps). Sometimes

another peak occurred around 5700 cycles per second (cps), which the author surmised occurred when the

larynx pipe was energized strongly enough that its natural octave began to appear. There were similar

38 Schoen, M. (1921). An Experimental Study of the Pitch Factor in Artistic Singing. Ph.D. Dissertation: University of Iowa, August, 1921.

18

indications for female voices but with the following exceptions: the high formant centered higher around

3200 cycles per second (cps); and the coloratura had almost no high formant yet the tone quality was

deemed "good" because of its "purity".39

Twenty five years later, at the 51st conference proceedings for the Acoustical Society of America,

Bartholomew suggested a classification of singer tones was necessary. Spectrographic and X-ray studies

of singing would allow for voice classification according to the singers voice quality, the singers

expressed mood, and the vowel sung by the singer. Bartholomew proposed twenty-seven classifications

of physiological differences visually noted in x-rays coupled with acoustic differences found in

spectrograms.40 Fry (1956) immediately responded with 27 voice classifications, but based the system on

three specific voice types light, lyric, and dramatic. Although a definition of these three voice types is

not provided, the general thought was that light described a voice that did not have a professional quality

to the sound perhaps lack of the singer's formant (Fs). Lyric and Dramatic voices represented opposites

of the professional voice spectrum. The three types were determined by the position of the larynx and the

configuration of the epiglottis, pharynx, and root of the tongue. Additional factors taken into

consideration were the mood of the singer and the vowel being articulated.41

Rshevkin (1956) recorded male voices singing vowels /u/, /a/, /i/, and /o/ on pitches ranging from

94 cycles per second (cps) to 490 cycles per second (cps) for duration of approximately 0.1 seconds.

Harmonic analysis revealed two distinct increases within two narrow bands of spectrum; 400-600 cycles

per second (cps) and 2200-2800 cycles per second (cps) which were not present in untrained baritones.

The higher formant frequency in the 2200-2800 cycles per second (cps) region was labeled the singer's

formant (Fs). Listeners described voices with the singer's formant (Fs) as metallic. Rshevkin suggested

that these peaks occurred only at the beginning of the vowel which the trained singer learned to modify to

39 Bartholomew, W.T. (1934). A physical definition of good voice-quality in the male voice. Journal of the Acoustical Society of America, 5 (3), 25-33. 40 Bartholomew, W. (1956). A basis for the acoustical study of singing. The Journal of the Acoustical Society of America, 28 (4), 757. 41 Fry, D. B. (1956). A basis for the acoustical study of singing. Program of the Fifty-First Meeting of the Acoustical Society of Americas Joint Meeting with the Second ICA Congress. Cambridge, Massachusetts, 34.

19

the vowel singing position. These results agreed with the findings of his earlier research (1927) and

those of Bartholomew who found a high singer's formant around 2800-3200 cycles per second (cps).42

Delattre (1958) felt the work of correlating voice formants with types and classes of voices had not

yet been successfully accomplished. The design of this study was not provided, but through an acoustic

articulatory comparison of vowel color and its effect on voice quality, Delattre reached the conclusion that

the quality of a singer's voice seemed to be characterized by the two or three formants whose frequencies

are just above the vowel formants.43

Arment's (1960) dissertation sought to compare the spectra of vowel tones with the perceptual

designation of the same tones on a bright to dark hierarchy. For the initial pilot study, participants (N = 2

sopranos with perceptually different tone qualities) were asked to sing four different pitches (D4, A4, D5,

F#5) on three different vowels (/i/, /a/, /u/) for a duration of four seconds per tone. The recordings were

made in an 8' x 10' acoustically dead room. To make the perception tape, the tones had both their onset

and offset trimmed leaving a two second tone. Auditors (N = 6 voice teachers and singers) were asked to

rate the vowel on a bright to dark ranking scale of: 1) very bright, 2) moderately bright, 3) neither

predominantly bright or dark [neutral], 4) moderately dark, or 5) very dark. Analysis of the auditors'

preferences included: 1) brightness to darkness rating for each vowel, 2) brightness to darkness rating for

each pitch, 3) brightness to darkness ratings for each vowel on each pitch, 4) brightness to darkness

ratings for each singer, and 5) brightness to darkness ratings for each vowel as sung by each singer.

Those tones which received the highest agreement on the dark to bright hierarchy were chosen for spectral

analysis, including identification of formants and intensities of harmonics.

Spectral analysis of the tones, which the auditors found to be very bright, revealed narrow

formants. The second formant (F2) was high in intensity and overall high harmonics. The dark vowel

spectra had broad formants, a third formant (F3) low in intensity, and a broad formant between 3000 and

5000 Hz. Another variable, two different singers with perceptually different tone qualities, was apparent

in the overall spectra (no definitive information is given regarding this statement).

The primary study recorded participants (N = 5 sopranos with a minimum of five years of vocal

training) singing D4, F#4, B4, D5, C#5, A4, G4, and E4. Each tone was sung on each of six vowels; /i/,

/e/, /a/, /o/, /u/, and //. The participants were asked to sing specific tones on a specific vowel in a 42 Rshevkin, S. N. (1956). Some results of the analysis of singing voice. Program of the Fifty-First Meeting of the Acoustical Society of Americas Joint Meeting with the Second ICA Congress. Cambridge, Massachusetts. 34-36. 43 Delattre, P. (1951). The physiological interpretation of sound spectrograms. Publication of the Modern Language Association (PMLA), 66 (5), 864-875.

20

particular voice quality bright, dark, or neutral. Each singer was given time to study the required order

of tasks and then given time for a practice run prior to the official recording. To aid the participant in

maintaining the intensity level between singing tasks, a decibel meter was positioned in the participant's

sight line. The target intensity level was 75-80 dB. The participants were recorded in the same 8' x 10'

acoustically dead room with a microphone thirty-two inches from the singer and forty-eight inches from

the floor.

The listening participants (N = 16 singing teachers and graduate level singers, n = 8 men and n = 8

women) were asked to evaluate a series of tones on a Likert 10 point scale from extremely bright to

neutral to extremely dark. Each tone in the series was to receive its own evaluation although the auditor

was going to hear six tones at a time. Spectral analysis of each tone was completed for all harmonic,

formant, and vibrato data. These spectral data were cross referenced with the listening participants'

answers. Arment concluded the brightness or darkness of a tone may be regarded as a continuum of tonal

characteristics44. The brightness to darkness continuum might be influenced by the vowel, the intensity,

and/or the pitch of the tone, but ultimately it stands alone as a significant descriptor of the tone. Varying

loudness of tones showed no effect on the brightness or darkness of tones. However, vowel did seem to

have a direct effect on the brightness or darkness of tone. Just as in the pilot study, bright tones had

strong high harmonics whereas dark tones had strong low harmonics. Bright tones had narrow formant

bands in comparison to wide banded dark tones. Tones which ranked the brightest showed greater

intensity of the second formant (F2) and an increase in the amount of harmonics in the tone.45

Coleman (1973) investigated exactly what physiological components define the quality of a

speaker's voice such that the speaker's sex is known. Two experiments were devised in which participants

(N = 40 university students, n = 20 males and n = 20 females) were recorded speaking a variety of speech

tasks and repeated some of the tasks using a laryngeal vibrator. The recordings were analyzed and the

vocal tract resonances (VTR) and laryngeal fundamental frequencies (LFF) were computed for each

participant. The first perception test utilized five-second samples from each participant played

backwards. In this test, auditors' (N = 17 university students) responses were significant (p > .01) with

94% accuracy in identifying the sex of the sample with respect to the laryngeal fundamental frequency

44 Arment, H. (1960). A Study By Means of Spectrographic Analysis of the Brightness and Darkness Qualities of Vowel Tones in Womens Voices. (University Microfilms No. AAG6002989). 45 Ibid.

21

(LFF). Accuracy dropped to 56% when the sex of the sample was compared to the average mean of the

vocal tract resonances (VTR).

The second perception test utilized the laryngeal vibrator samples which had the highest vocal

tract resonances (VTR) for the females (n = 5) and the lowest vocal tract resonances (VTR) for the males

(n = 5). Only two pitches were used for the samples 240 Hz and 120 Hz. The samples had equal

representations of the following descriptors: low vocal tract resonances (VTR) and low laryngeal

fundamental frequencies (LFF), high vocal tract resonances (VTR) and high laryngeal fundamental

frequencies (LFF), high vocal tract resonances (VTR) with low laryngeal fundamental frequencies (LFF),

low vocal tract resonances (VTR) with high laryngeal fundamental frequencies (LFF). The auditors (N =

25 university students) were asked to determine the sex of the speaker and the results showed correct sex

identification 245 out of 250 times in the first two descriptors above (those in which the VTR and the LFF

are indicative of the same sex). When the descriptors were jumbled, male characteristics (low VTR and

low LFF) were perceptually more prominent. The results of these experiments led Coleman to the

conclusion that laryngeal fundamental frequency plays a heavier role in our ability to discern between

male and female speakers.46

Teie (1976) used a variety of singers (N = 31, n = 5 male first year voice students, n = 5 female

first year voice students, n = 5 male fourth year voice students, n = 5 female fourth year voice students, n

= 3 male untrained singers, n = 3 female untrained singers, and n = 5 voice faculty members) to look at

the effect of vocal training on presence of the singer's formant (Fs), an increase in energy in the 2800-

3200 Hz range. Each participant was recorded singing the vowels /a/, /i/, and /u/ on two pitches. The

male participants sang at 160 Hz (E3) and 288 Hz (D4) and the female participants sang on 288 Hz (D4)

and 512 Hz (C5). These pitches were chosen to represent the upper and lower voice registers of both the

male and female participants. It was also deemed important for one of the pitches to be sung by all

participants (288 Hz, D4). The participants were instructed to sing at full volume and to vary the distance

of their mouth to the microphone by watching an oscilloscope so that 125 dB was maintained. The

recordings were conducted in a sound proof speech laboratory room.

Each of the participant's six samples was analyzed through spectrography for the fundamental

frequency (F0) and the presence of partials in the tone. Teie concluded that the amount of training affects

the frequencies higher than the second formant (F2), most specifically the range of 2 kHz to 4 kHz. The 46 Coleman, R. (1973). A comparison of the contributions of two vocal characteristics to the perception of maleness and femaleness in the voice. STL-QPSR, 14 (2-3), 13-22.

22

training effect was present in the intensity levels of the tones for both trained and untrained participants

had similar configuration and breadth within the singer's formant (Fs) range, 2800-3200 Hz. Little

difference between all of the subsets of participants was apparent in the F1 and the F2 when the singers

were singing the same vowel at the same pitch. In the trained singers' samples, there was spectral energy

peaks in the 6 to 8 kHz region. Most interesting was that the untrained singer's produced tones with

almost as prominent singer's formant (Fs) as did the trained singers on the /i/ vowel. This suggests singers

should strive to have the /i/ vowel quality in all vowel sounds to enhance the singer's formant (Fs) region.

Teie went so far as to conclude the essence of consistent tone quality is the ability to color all vowel

sounds with an /i/ resonance.

Teie felt his results were circumspect due to the low participant number for each subset category.

Additionally, the dynamic level chosen may have had an impact on the results and therefore a greater

variety of dynamic levels would have provided keener insight as to this effect. The Fs was inconsistent in

the female singers' spectra. In closing, Teie conjectured as to the effect consonants would have on the

presence of the singer's formant (Fs).47

To examine vocal registration, Cleveland (1977) recorded male participants (N = 8 professional

Swedish singers) singing the vowels /i/, /e/, //, /o/, /u/ on the pitches C3, F3, A3, E4. A listening test was

designed with three hearings of each vowel vocalization presented in two twenty-five minute sessions

each separated by a thirty-minute break (five vowels x four pitches x eight subjects). Some vowel sounds

were synthesized by a source-filter network. Auditors (number unknown) were asked to determine the

voice classification of the singers as bass, baritone, or tenor.

Source spectra, formant frequency, and sonogram measurement were employed on the vowel

vocalizations. The information showed the voice classification was dependant on vocal tract size and

dimension, for example, the vocal tract length of basses singing /i/ was nineteen centimeters as compared

to tenors at 15.5 centimeters. Cleveland also found timbre type classification to be strongly influenced by

formant frequency and suggested that its importance outweighed pitch. The correlation between formant

frequency of spoken vowels and sung vowels was quite high and could be useful in future voice

47 Teie, E. (1976). A comparative study of the development of the third formant in trained and untrained voices. (Doctoral Dissertation, University of Minnesota, 1976). Dissertation Abstracts International, 37, (10A), 6135.

23

classification. Since vocal timbre exists at an earlier age than full range capability, Cleveland suggested it

is a better indicator of voice classification.48

Magill and Jacobsen asked professional singers (n=15) and college music students (n=15) to

identify their voice classification and then recorded them singing sustained vowels and major arpeggios

appropriately pitched for their self-proclaimed voice categories. Analysis of the recordings showed the

presence of increased spectral energy in the range of the singers formant (Fs) in both males and females

and in all voice categories. There was more singers' formant (Fs) presence in the male voices which

Magill and Jacobsen hypothesized may have been due to a lower first formant (F1) that allowed for a

greater number of harmonics to fall within the area of the singer's formant (Fs) frequency envelope. The

strength of the energy in the singer's formant Fs) region showed a direct correlation to the participant's

amount of training and experience.49

Colton and Estes (1979) recorded participants (N is not provided) singing in four separate voice

qualities on selected pitches throughout their vocal range. Auditors (N is unknown) had a high degree of

accuracy in identifying the participants' modes of phonation, even at the ends of the vocal ranges. The

acoustical results of the recordings showed definite frequency bandwidths, specific resonant peak

locations with representative spectral envelopes to dynamic ranges. Physiological results were equally

definitive of each vocal mode. The results suggested the unique features of each voice mode could

provide singers with a roadmap toward a variety of healthy vocal modes of phonation that in turn would

offer singers multiple voice qualities.50

Murray (1979) explored the presence of jitter in female spoken phonation as compared to sung

phonation. Jitter is the presence of irregular periodicity in the action of the vocal folds and is often

perceived as hoarseness. Female singers (N = 4) were recorded speaking the vowel /a/ and then singing

the vowel /a/ in four different conditions (conditions are unknown). The recorded samples were measured

for frequency perturbation (jitter). A panel of participants (N is not provided) were asked to listen to the

recorded samples and determine if the samples were sung or spoken. Perception participants were unable

48 Cleveland, T.F. (1977). Acoustic properties of voice timbre types and their influence on voice classification. Journal of the Acoustical Society of America, 61, 1622-1629. 49 Magill, P., Jacobson, L. (1978). A comparison of the singing formant in the voices of professional and student singers. Journal of Research in Music Education, 26 (4), 456-469.

50 Colton, R., & Estill, J. (1979). Elements of quality variation voice modes and singing. Acoustical Society of America Supplement, 1(66), Fall 1979, 55-56.

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to discern differences between spoken and sung vowels. The analysis results showed less jitter in spoken

vowels than that of the sung vowels.51

Hertegard et al. (1990) used sung vowels to investigate "open" versus "covered" vowels.

Participants (N = 11 professionally trained male singers, n = five tenors, n = three baritones, and n = 3

basses) were recorded singing in both head and covered technique with a variety of acoustical equipment

in many conditions. Participants received no training as to the difference between covered and open

singing technique as all participants confirmed they had received such training from singing experts

during their years of vocal study.

The first study utilized a flexible fiberoptic endoscope to allow video of the working mechanism

during both the open and covered singing of a one octave scale on the vowel /ae/. The participants were

instructed to choose a scale that would cross the passaggio near the top of the scale. At the end of the

scale the participants were asked to sing an octave interval to return to the starting pitch. The participants

then sang a sustained note on the vowel /ae/ near the passaggio. No directions were given for dynamics in

either task.

The resulting recordings (both audio and visual) were observed and listened to by participants (N

= 3, n = two phoniatricians and n = one logopedist) to evaluate whether or not the flexible fiberoptic

endoscope recordings presented any differences between open and covered techniques. The designated

form for the participants conclusions had the categories no difference and obvious difference for the

visual recordings and obvious, slight, or nil for the audio recordings. Obvious differences were noted

by the panel participants in the recordings between open and covered vocal production. Visual analysis

revealed the soft palate was consistently higher in seven of the subjects in covered singing. Ten of the

subjects widened their pharynx for covered singing. Of the five participants in which the larynx was

clearly visible, all five participants widened the laryngeal ventricles and tilted the larynx forward in

covered singing.

In the second study, participants (N = 7 males singers) wore a Rothenberg mask

(pneumotachograph mask) and were recorded singing /pae/ at a pitch of their choosing near the passaggio,

alternating between open and covered singing. The recorded samples were inverse filtered and produced

a transglottal air-flow wave form (FGG) for analysis of the first and second formant (F1, F2). A flow

glottogram graph (FGG) shows specific activity of the vocal fold cycle peak-to-peak flow amplitude in 51 Murray, T. (1979). Vocal jitter in singers voice. The 98th Meeting of Acoustical Society of America, November 1979, Salt Lake City, Utah, 55.

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milliliters per second, glottal leakage in milliliters per second, period time in milliseconds, and duration of

the quasi-closed phase in milliseconds. The results obtained from the inverse filtering were varied.

Subglottal pressure (Ps) and sound pressure level (SPL) showed little or no variation between covered and

open singing. The first formant (F1) was generally lower during covered singing whereas the second

formant (F2) was generally higher in covered singing. Also, the voice source appeared different between

open and covered singing although no definitive information was detailed.

The participants from the second study also participated in the third study. Participants were

recorded singing a sustained vowel /ae/ near the passaggio at a pitch of their choosing in both open and

covered technique. Spectral analysis of these recordings gave information regarding fundamental

frequency (F0), the level of harmonics, and the frequencies of the first and sometimes second formant (F1,

F2). The spectrogram of same participants open singing was superimposed on the participant's covered

singing spectrogram for six of the seven participants. The energy of the singers formant region was

unchanged between open and covered production. The highest energy level was located at the harmonic

closest to the first formant (F1), but it was unclear whether this was in open or covered singing.

When the participant used covered technique to equalize the passaggio, the frequency of the fourth

harmonic (F4) would often agree with the frequency of the second formant (F2). Perhaps a relationship

existed between the passaggio and this match. Was this result due to the increased loudness (averaging

eight dB) in covered singing versus open singing? Another factor in the sound spectrum was that the

amplitude of the fundamental frequency (F0) was higher in covered singing, just as the first formant (F1)

was lower. These changes were speculated to be due to changes in the voice source. Most importantly,

these combined results suggested that covered singing reduced strain on the vocal mechanism and could

prevent hyper-functional strain of the larynx.52

Detweiler (1993) designed a study to confirm Sundbergs concept of the singers formant (Fs).

The singer's formant (Fs) and the source of the singer's formant (Fs) resonance has a direct relationship

between the ventricular spaces in pulse phonation, and the laryngopharyngeal outlet cross section area

which would result in a 6:1 ratio. One tenor and two baritones (N = 3) were recorded singing during

laryngeal stroboscopy and an MRI procedure. Although the participants produced consistent energy

increases in the singer's formant region (Fs) in all procedures, and in both modal and pulse modes, these

participants did not meet the 6:1 ratio requirement. However, the MRI images were obtained while the 52 Hertegard, S., Gauffin, J., Sundberg, J. (1990). Open and covered singing as studied by means of fiber optics, inverse filtering, and spectral analysis. Journal of Voice, 4, 220-230.

26

participant was lying down, which produced a vertical orientation. The result was an overestimation of

the area to be measured (Sundberg, 2003). However, this study confirmed the existence of singer's

formant resonances (Fs1 and Fs2) in the pulse registers of these participants.53

Female barbershop tenors have a very specific voice quality which is perceived as light and having

very little vibrato. Abbott (2001) recorded female barbershop tenors (N = 27) speaking and singing

voices. Acoustic analysis of the recordings revealed consistencies throughout the participant group. The

female barbershop tenors' voices were characterized with an increased fundamental frequency variation in

their speaking voice when compared to existing data for similar aged women. When singing, the

participants had great variability in the upper passaggios, higher spectral energy in the fundamental and

lower harmonics, and vibrato presented in 25% of the time recorded (extremely low percentage).54

Registration

Helmholtz (1885) believed the tension of vocal folds not only determined the pitch of the tone, but

also which register the tone originated. He also asserted the thickness of the vocal folds played a part in

the sound of the tone, for example, the head voice was thought to be the product of the drawing aside of

the mucous coat below the chords (sic) thus rendering the edge of the chords sharper, and the weight of

the vibrating part less, while the elasticity is unaltered.55 The breast voice (chest or modal voice) was a

result of the tissue below the vocal folds pulling at the bottom of the vocal folds, thereby making them in

effect heavily weighted.56 The articles that we are about to examine are built on the foundation Hemholtz

provided for us, yet many surprises are in store.

Fillebrown (1911) acknowledged that head tones, chest tones, closed tones, and open tones were

accepted vernacular of the day, but strongly advocated that registers were not a natural feature of the

voice. He supported his claim through a series of statements by surgeons and professional singing

teachers. These included Manuel Garca, the creator of the laryngoscope, who was reported to have

confirmed Fillebrown's belief in the "one voice" system.57 Although Fillebrown purported no vocal

53 Detweiler, R. (1994). An investigation of the laryngeal system as the resonance source of the singers formant. Journal of Voice, 8 (4), 303-313. 54 Abbott, S. E. (2001). Acoustic evaluation and analysis of the female barbershop tenor voice. Unpublished doctoral dissertation, The Florida State University. 55 Helmholtz, (1885), 101. 56 Ibid. 57 Fillebrown, (1911), 2.

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registers, he provided this definition of registers: a series of tones of a characteristic clang or quality,

produced by the same mechanism.58

Janwillem van den Berg (1963) agreed that vocal registers were pr