5070- Wk 3

What is intensity in terms of sound?

The amplitude or "size" of a sound wave; measured in decibels (dB).

What is the lay term for intensity?

Volume (e.g., “turn the volume up”).

How is intensity measured?

With a sound level meter in dB.

What is loudness?

A perceptual characteristic judged by a listener; cannot be objectively measured.

What links loudness and intensity?

A psychophysical scale; shows perceived loudness (Y) vs. intensity in dB (X).

What is recruitment?

Abnormal growth in loudness perception, common in hearing loss.

At which frequencies is human hearing most sensitive?

1000–5000 Hz.

What scale do audiometers use?

Hearing Level (HL), not Sound Pressure Level (SPL).

What is a phon?

A unit to match perceived loudness to 1000 Hz tone SPL.
(E.g., 50 dB SPL @ 1000 Hz = 50 phons)

What are Fletcher-Munson contours?

Equal-loudness curves showing how loudness perception varies by frequency and intensity.

General rule: how much louder does a sound seem with 6–10 dB added?

It’s perceived as twice as loud.

What is 1 sone equivalent to?

40 dB SPL @ 1000 Hz.

How many dB needed to double perceived loudness?

Add 8–10 dB.

How many dB to halve perceived loudness?

Subtract 8–10 dB.

Below what duration does tone length affect loudness perception?

500 milliseconds (especially 15–150 ms).

Why does longer duration = more audible?

The ear integrates more sound energy over time.

What is Root Mean Square (RMS)?

A mathematical way to calculate the average amplitude of a waveform.

Why use RMS for sound?

Mic signals fluctuate (+/-), RMS gives a stable, positive value.

What is acoustic power?

The total energy radiated in watts.

What is intensity?

Power per unit area; decreases with distance.

What is the inverse square law?

Intensity ∝ 1 / (distance²).

What drives speech intensity?

Subglottal pressure.

How does loud speech differ?

More pressure, larger vocal fold movement, stronger articulator bursts.

What is a Vocal Range Profile (VRP)?

Graph showing dB range across F0 range; used more in Europe.

What is frequency?

The number of waveform cycles per second; measured in Hz.

What is pitch?

A subjective perception of frequency; cannot be measured directly.

What is the mel scale?

Perceptual pitch scale where 1000 Hz @ 40 dB = 1000 mels

How do Hz and mels relate at high frequencies?

Hz must increase more for the same change in mels.

What are difference limens (DL)?

Smallest detectable change in frequency.

How does frequency affect DLs?

DLs increase with higher frequency and lower intensity.

What is a fundamental frequency (F0)?

The lowest frequency in a complex tone; perceived as pitch.

What are harmonics?

Integer multiples of the F0.

What is the “missing fundamental” phenomenon?

Pitch is still perceived even if F0 is absent due to brain interpolation.

What is an octave?

Doubling or halving of frequency (e.g., 400 Hz → 800 Hz).

How many semitones in an octave?

12 semitones.

Are semitone steps linear?

No—each step is about a 5.9% increase in Hz; nonlinear but perceptually equal.