Acoustics and Sound Flashcards

Which phenomenon describes the bending of sound waves around obstacles or through openings?

Answer: Diffraction

Diffraction is the bending of sound waves around corners or through openings, allowing sound to be heard around barriers.

A patient reports that a 1000 Hz tone sounds like it has a pitch of only 500 Hz. This distortion is an example of:

Answer: Diplacusis

Diplacusis is a hearing distortion in which the same sound is perceived as having different pitches in each ear or at an incorrect pitch.

What is the speed of sound in air at approximately 20°C (68°F)?

Answer: 343 m/s

Sound travels at approximately 343 meters per second in air at 20°C under standard atmospheric conditions.

The acoustic reflex threshold (ART) is typically how many dB above the pure-tone threshold in a normal ear?

Answer: 70–100 dB SL

In normal-hearing ears, the acoustic reflex is elicited at approximately 70–100 dB above the pure-tone threshold (sensation level).

Which measurement best describes the subjective loudness level of a complex sound compared to a reference 1000 Hz pure tone?

Answer: Phon

The phon is a unit of loudness level that equates any sound to the dB SPL of a 1000 Hz pure tone judged equally loud.

When two sounds of slightly different frequencies are presented simultaneously, listeners perceive a rhythmic pulsing called:

Answer: Beats

Beats arise when two tones close in frequency combine, producing amplitude fluctuations at a rate equal to the difference between their frequencies.

In a free-field environment, sound pressure level decreases by approximately 6 dB for every:

Answer: Doubling of distance from the source

The inverse square law states that in a free field, SPL drops ~6 dB each time the distance from a point source doubles.