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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?