Airflows for Speech and Voice

Lab 4

AirflowVocal tract= aerodynamic sound generator &

resonator Airflow changes due to vowel & consonant

articulation Evaluation of airflow can provide insight into

speech system dysfunction & efficiency• Precision of diagnosis

• Documenting change due to therapy

• Biofeedback to patients with voice or articulation disorders

Airflow

Flow= movement of a gas through a given area in a unit of time.

Units of measurement- liters or milliliters/sec or per minute

Rate of flow is proportional to pressureRate of flow is inversely proportional to the

resistance of the structure in which the gas is moving through

Air Volume

All air for speech comes from the lungsAir volumes used in speech = Change in

lung volumeImportant: How much volume does it take

to complete a speech task? Compared to total vital capacity?

Airflow Instrumentation

Face masks-

All air must be measured

Only air pertaining to speech

Articulation must not be impeded

No leaks around circumference of mask

Airflow Instrumentation

Airflow Transducers Transduce an airflow into an appropriate

electrical signal Pneumotachograph

• Pressure drop is measured across a resistance to airflow (wire mesh screen)

Warm wire anemometer

Calibration

Flow is calibrated by observing the systems

output when known airflows are passed

through the transducer Rotometer (flow meter)

Syringe (1 liter)

• Aerophone calibration

Laboratory 4Part I:

Calibrate aerophone F300 flow head if necessary

Measure mean flow (flattest portion of flow waveform)

Normal airflow rates:

= .100 ml/sec; = .120 ml/sec (estimates..remember there is a standard deviation of about .56 ml/sec)

Laboratory 4Part I (Cont.):

Onset of flow = time before initiation of vowel production

Offset= time after vowel production has stopped Stability of trace-

• Hint- look at how much volume has been expended vs. the time for each trace

Oscillating flow trace- measure in the middle of trace for flow value

Laboratory 4

Polypoid Airflow Record: Measure mean airflow at about the middle of

the waveform (measure highest and lowest point and estimate middle)

Compare to norms Remember the relationship: Greater irregularity

in the signal, greater noise- Is this signal regular?

Laboratory 4

Polypoid Airflow Record (cont.) Airflow trace should be periodic to mirror

glottal opening and closing More aperiodicity in the flow trace = increased

laryngeal inefficiency MPT (maximum phonation time)=

vital capacity/ flow (L/sec)

Laboratory 4Part II: Sustained phonation airflow

Use Aerophone II- Choose Mamimal Sustainbed phonation task and sustain /a/ for as long as you can.

Cursor in on the beginning of the airflow waveform, mark and then mark at end of the waveform

Measure (calculate data) Report mean airflow for sample Now collect the same /a/ , but use a louder voice. Compare comfortable and louder phonation airflows

Laboratory 4

Part II: Use /pa/ task (labeled C)

Label peak pressure & vowels

Frequency response- Should see sharp rise of

flow after release of /p/ and oscillation of flow

to represent glottal pulsing

Mean peak airflow for the /p/ (not the vowel)

Laboratory 4

Part II: Normal subject-(labeled D) “Today is a sale”

Measure peak airflow /t/, /d/, /s/, /z/

Ripples in the flow signal indicate voicing

Articulation of /l/- decrease in flow. Why?

Plosives vs. fricatives- Voicing? Peak strength?

Mean airflow in connected speech? Variable?

Laboratory 4

Part II: Dysarthric speaker (labeled E)

• What are the differences in this production of “Today is a Sale” Compared to the normal sample

• Duration

• Flow release of fricatives

• Slower or faster?