Physiology: Loudness and vocal intensity

What is loudness ?

perceptual event related to: vocal intensity or amplitude of sound or sound pressure level (db SPL)

What does loudness correspond to?

alveolar pressure

How to change loudness (vocal intensity) examples

increase loudness, decrease loudness, and whisper

we changing loudness by changing: aerodynamic and muscular forces

Aerodynamic forces:

Change volume of air

Change alveolar pressure

Muscular forces:

Change medial compression WHICH INFLUENCES→Resistance to airflow

We change loudness by changing: recall volume requirements

Quiet: use 10-15% of vital capacity above resting volume. or 50-55% VC

Convo: 20-25% of vital capacity above resting volume.or about 60-65% VC

Loud: Use 40+% of vital capacity above resting volume line or around 80+% VC

We can change loudness by changing: Recall PTP pressure requirements for loudness

quiet: 3-6 cmH20

convo- 7-10 cmh20

loud: 11-80 cmh20

We can change loudness by changing: Recall medial compression

Muscular force with which vfs are "pressed" together at midline

What does it mean if we increase medial compression?

Then:

“Firm” glottal closure

Result:

Greater resistance to air flow and alveolar pressure

What does it mean if we decrease medial compression?

Then:

“Relaxed” glottal pressure

Result:

less resistance to air flow and alveolar pressure

To increase loudness (vocal intensity)

Change aerodynamic forces:

Increase volume of air, increase alveolar pressure

Change muscular forces:

Increase medial compression

In order to: increase alveolar pressure

To increase medial compression we must:

Increase force of Adductors resulting: “firm” glottal closure

Result: increase alveolar pressure (PTP) required to initiate glottal cycle (eg. 11+ Cm H20)

as a result of greater air pressure:

Exhaled air velocity also increases

Result:

Vfs close with greater force

Possible concern: LOUD for long periods may temporarily “damage” vfs

To decrease loudness (vocal intensity)

Aerodynamic forces:

decrease volume of air

decrease alveolar pressure

Muscular forces:

Decrease medial compression

In order to:

Decrease alveolar pressure

To decrease medial compression

Minimize force of Adductors resulting in “Relaxed” glottal closure

Result: decrease alveolar pressure (PTP) required to initiate glottal cycle (e.g. 3 cm H20)

as a result of less air pressure

- Exhaled air velocity also decreases

- Result: vfs close with less force

In contrast to LOUD:

Soft or conversational loudness for long periods less likely to damage vfs

To initiate whisper, contract:

Lateral cricoarytenoids

Action:

Vfs adducted, but triangular gap left between arytenoids

Result: creates “whisper triangle”

To whisper (minimal vocal intensity)

- Aerodynamic forces: Maintain steady air flow

-Muscular forces: Adjust vf position so no phonation occurs -

- BUT: airflow becomes turbulent and audible as: hissing sound