Transcript Airflows for Speech and Voice

Airflows for Speech and Voice
Lab 4
Airflow
 Vocal tract= aerodynamic sound generator
& resonator
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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 pressure
 Rate 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 lungs
 Air volumes used in speech = Change in
lung volume
 Important: 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
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Only air pertaining to speech
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Articulation must not be impeded
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No leaks around circumference of mask
Airflow Instrumentation
 Airflow Transducers
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Transduce an airflow into an appropriate
electrical signal
Pneumotachograph
• Pressure drop is measured across a resistance to
airflow (wire mesh screen)
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Warm wire anemometer
Calibration
 Flow is calibrated by observing the systems
output when known airflows are passed
through the transducer
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Rotometer (flow meter)
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Syringe (1 liter)
• Aerophone calibration
Laboratory 4
 Part I:
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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 4
 Part I (Cont.):
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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:
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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.)
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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 4
 Part II: Sustained phonation airflow
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Use Aerophone II- Choose Mamimal Sustainbed
phonation task and sustain /a/ for as long as you can.
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Cursor in on the beginning of the airflow waveform,
mark and then mark at end of the waveform
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Measure (calculate data)
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Report mean airflow for sample
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Now collect the same /a/ , but use a louder voice.
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Compare comfortable and louder phonation airflows
Laboratory 4
 Part II:
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Use /pa/ task (labeled C)
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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:
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Normal subject-(labeled D) “Today is a sale”
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Measure peak airflow /t/, /d/, /s/, /z/
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Ripples in the flow signal indicate voicing
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Articulation of /l/- decrease in flow. Why?
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Plosives vs. fricatives- Voicing? Peak strength?
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Mean airflow in connected speech? Variable?
Laboratory 4
 Part II:
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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?