COMD 5070 EXAM 2 STUDY GUIDE
Average Air Flow Calculation - Average flow formula:
️ Flow = Air/Time - If 1 liter of air is used and the phonation lasts for 5 seconds, the calculation is: - Average flow = 1 liter / 5 seconds - = 0.2 liters/second (or equivalent to 200 cc/second) - Note...
- If 1 liter of air is used and the phonation lasts for 5 seconds, the calculation is:
- Average flow = 1 liter / 5 seconds
- = 0.2 liters/second (or equivalent to 200 cc/second)
- Note: Flow at a given instant may vary, meaning the average flow does not capture transient changes
during phonation.
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U-Tube Manometer
- How it works:
✔️ Measures static pressure.
- It consists of a tube in the shape of a 'U'. Water in both arms of the tube is initially at the same level
until pressure is applied. The difference in height of the water columns in the two arms indicates the
pressure exerted:
- Measure the height difference (in centimeters of water displaced) to determine the amount of
pressure applied.
- Best uses:
✔️ Can be used to calibrate equipment used to measure pressure.
- It is low-tech and allows for easy visual measurement of pressure changes.
- Limitations:
✔️ Rather crude;
- Measurement relies on visually assessing the height difference between the water columns, making it
impractical for rapidly changing pressures (as in speech).
, - Subtle pressure changes are difficult to detect accurately.
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Pressure Transducer
- Function:
✔️ Can measure the air pressure in a given space, such as intraoral air pressure during speech
production.
- It is used for aerodynamic measures of speech.
- Setup:
- A clear polyurethane tube is placed in the corner of a person's mouth, and they speak while keeping
their lips sealed around it.
---
Measuring Speech Breathing
- Sources of Measures:
✔️ Most speech measures come from the oral cavity; some come from the nasal cavity.
- Setup: A tube inside the mouth connects to a transducer located outside.
- Pressure Patterns in Speech:
✔️ Just inside the mouth:
- Pio (intraoral air pressure):
- Vowels: Equal to atmospheric pressure.
- Fricatives: Elevated air pressure.
- Stop consonants: Highest air pressure.
- Movement of Ribcage and Abdomen:
, ✔️ Increases and decreases in the volume of the lungs:
- Inhale: The diaphragm flattens, expanding lung volume and decreasing pressure, allowing air to enter.
It also pushes down on abdominal viscera, causing belly expansion.
- During typical breathing: The ribcage and abdomen typically expand or contract together.
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Subglottal Pressure (Pₛ or Psub)
- Definition:
✔️ Pressure that the lungs provide that travels up the trachea to the larynx.
- Measured directly below the larynx and it serves as the driving pressure for phonation and speech.
This pressure can be difficult to measure directly.
- Estimation:
✔️ Measured by assessing intraoral air pressure at specific times when it equals the subglottal
pressure:
- This occurs briefly during the production of certain sounds (e.g., voiceless bilabial plosive /p/ or
vowels).
- During production of /p/:
- Vocal folds are abducted, leading to no pressure drop at the larynx and equalizing pressure
throughout the system.
- Alternative Measurements:
- Tracheal puncture:
- Allows direct measurement during speech using a miniaturized pressure transducer placed inside the
trachea. However, it is an invasive medical procedure and difficult to recruit volunteers for such studies.
- Esophageal (balloon) pressure:
- Not commonly used. Measures pressure from the shared wall between the trachea and esophagus
by placing a sensor in the esophagus. This system tends to be impractical.
, ---
Subglottal Pressure for Speech
- Normal speaking pressure:
✔️ 5-7 cmH₂O typical for normal speech.
- Loud speaking pressure:
✔️ 15-20 cmH₂O for very loud speech.
- Association between Psub and Sound Pressure Level (SPL):
- ✔️ Lower pressure correlates with pulse register; higher pressure with falsetto:
- In pulse register, vocal folds oscillate with less stress and lower pressure, while falsetto may require
higher subglottal pressure to maintain tension and vibration frequency.
phonation threshold pressure what is it? ✔️PTP - pressure for folds to start vibrating
between 3-5 cmH2O needed to start
phonation threshold pressure: what influences it? ✔️less that 3-5 cm H2O needed to maintain it
• PTP increases with
- dehydration
- vocal fatigue
- why might this be?
phonation threshold pressure increases with dehydration, vocal fatigue, why might this be?
✔️dehydration: if vocal folds are dried out and less compliant, less flexible increase in the amount of
pressure needed to make them move
vocal fatigue: swollen, puffy bulky, more pressure needed to make oscillate
higher pressure for falsetto - why might this be? ✔️Vocal folds stretched very tightly
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