5070- Wk 3 Notes

What physical characteristic is intensity linked to?

Amplitude (the “size” of the sound wave).

What is the layperson’s term for intensity?

Volume

What unit is intensity measured in?

Decibels (dB).

What device measures intensity?

Sound level meter.

What is loudness?

The perceptual experience of intensity; judged by a listener.

Can loudness be measured by equipment?

Nope! It's subjective.

What links loudness to intensity?

A psychophysical scale (like phons or sones).

What is recruitment?

Abnormal loudness growth; not experienced with normal hearing.

What is a phon?

A unit that matches loudness of tones across frequencies to 1000 Hz reference.

50 dB SPL at 1000 Hz equals how many phons?

50 phons.

What are equal loudness contours?

Graphs showing perceived loudness (phons) across frequencies.

What frequencies is human hearing most sensitive to?

1000–5000 Hz.

What is a sone?

A unit of relative loudness at the same frequency but different amplitudes.

What is the reference point for 1 sone?

40 dB at 1000 Hz.

How do you double perceived loudness in sones?

Add 8–10 dB.

How do you halve perceived loudness?

Subtract 8–10 dB.

When does duration affect loudness perception?

For durations <500 ms, especially 15–150 ms.

Why does longer = louder (up to a point)?

The ear integrates energy over time.

What’s used to measure average sound amplitude mathematically?

Root Mean Square (RMS).

Why square the values in RMS?

To make all values positive before averaging.

What is acoustic power measured in?

Watts

What is intensity?

Power per unit area (Watts/m²).

What is the inverse square law?

Intensity decreases with the square of the distance from the source.

What drives speech effort?

Subglottal pressure.

What increases for louder speech?

VF collisions, articulator movement, oral pressure, stop burst force.

What does VRP measure?

dB range across the fundamental frequency (F0) range.

Is VRP used in typical SLP evals?

Nope, too time-consuming—used mainly for voice patients.

What is frequency?

Number of waveform cycles per second (Hz).

What is pitch?

Perceptual correlate of frequency.

Can pitch be measured by instruments?

No—it’s subjective.

What scale measures pitch perception?

The mel scale.

1000 Hz at 40 dB SPL = ?

1000 mels.

Pitch perceived as half = ?

500 mels.

Pitch perceived as double = ?

2000 mels.

What are DLs?

Smallest detectable frequency difference.

Do DLs increase with frequency?

Yes—especially at higher frequencies and lower intensities.

What is a complex tone?

A sound with multiple sine waves (harmonics).

What is the fundamental frequency (F0)?

The lowest—and often strongest—frequency in a harmonic series.

What happens if the fundamental is missing?

Pitch is still perceived—thanks, brain interpolation.

What defines an octave?

Doubling or halving of frequency.

How many semitones in one octave?

12

Are semitone steps linear in Hz?

Nope—each one is ~5.9% bigger than the last.