Airflows for Speech and Voice

1
Airflows for Speech and Voice

• Lab 4

2
Airflow

• Vocal 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

3
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

4
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?

5
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

6
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

7
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

8
Laboratory 4

• Part 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..remembe
  r there is a standard deviation of about .56
  ml/sec)

9
Laboratory 4

• Part 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

10
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?

11
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)

12
Laboratory 4

• Part 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

13
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)

14
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?

15
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?