IHS Acoustics and Sound 2

Question 1

What does RT60 (reverberation time) measure in room acoustics?

Accepted Answer

The time required for sound to decay by 60 dB after the source stops

Answer

RT60 is the time required for sound energy to decay by 60 dB after the source stops, serving as the standard metric for room reverberation and its impact on speech clarity.

Question 2

How does a higher signal-to-noise ratio (SNR) affect speech intelligibility for hearing aid users?

Accepted Answer

It improves speech intelligibility by making the signal stronger relative to background noise

Answer

A higher SNR means the desired speech signal is substantially louder than background noise, directly improving the listener's ability to understand speech, especially for those with hearing loss.

Question 3

What is the primary cause of acoustic feedback in hearing instruments?

Accepted Answer

Amplified sound from the receiver leaking back into the microphone and being re-amplified

Answer

Acoustic feedback is a closed loop where amplified sound from the receiver (speaker) escapes and re-enters the microphone, is amplified again, and creates the characteristic whistle or squeal.

Question 4

What is the key distinction between sound pressure level (SPL) and hearing level (HL)?

Accepted Answer

SPL uses a fixed physical reference (20 µPa); HL is referenced to average normal hearing thresholds that vary by frequency

Answer

SPL is referenced to a fixed pressure of 20 µPa across all frequencies, while HL adjusts for the ear's varying sensitivity so that 0 dB HL represents the average normal hearing threshold at each test frequency.

Question 5

In acoustics, what does one octave represent?

Accepted Answer

A doubling of frequency

Answer

One octave equals a doubling of frequency; for example, 500 Hz to 1,000 Hz is one octave, and 1,000 Hz to 2,000 Hz is the next octave.

IHS - International Hearing Society Practice Test

IHS - International Hearing Society Practice Test

IHS Acoustics and Sound 2