HEAR 657 Term 3 Chapter 5

Which statement(s) is/are true about early HA prescriptions?

• They tried to mirror the audiogram.

• They resulted in output that was too loud.

• They used linear amplification.

• They were too complicated to use.

Answer explanation

Early prescriptions were very simplistic because the fitting was crude.

Which statement(s) is/are true about Lybarger's Half-Gain Rule?

• It provided too much amplification.

• It tried to mirror the audiogram.

• It provided half as much gain as the HL.

• It is the basis of most modern HA prescriptions.

Answer explanation

The early prescriptions tried to mirror the audiogram which provided too much amplification.

Which statement(s) is/are true about the NAL linear prescriptions?

• It aimed to amplify LTASS so it was audible at all frequencies.

• It aimed to amplify LTASS so it's equally loud at all frequencies.

• It avoids the upward spread of masking.

• It avoids acoustic feedback.

Answer explanation

LTASS should have equal loudness, not equal audibility.

There's nothing in this prescription that would with acoustic feedback.

Which of the statement(s) is/are true about this image?

• Normal loudness growth is non-linear.

• Arrows indicate gain needed to approximate normal loudness growth.

• It demonstrates why compression is needed in HAs.

• People with SNHL have impaired loudness growth.

Answer explanation

Normal loudness growth is linear as indicated by the diagonal line (1:1 relationship between dB HL and loudness rating).

Which statement(s) is/are true about compression in HAs?

• Compression is a type of non-linear amplification.

• Compression provides more gain as input increases.

• Compression provides less gain as input increases.

• Compression can act on either the input level or the output level.

Answer explanation

Expansion provides more gain as input level increases.

Which statement(s) is/are true about dealing with HA output?

• Peak clipping can result in distortion.

• Peak clipping is a type of compression.

• Compression limiting has a high compression ratio.

• Compression limiting has a low compression threshold.

Answer explanation

Peak clipping doesn't use compression. Compression limiting has a high compression threshold because it's looking at the level of the output.

Which statement(s) is/are true about this image?

• It has a low compression threshold.

• It is linear for most input levels.

• It has a high compression ratio.

• It is an input/output function.

Answer explanation

It has a high compression threshold (110 dB SPL) and is an output compressor (compression limiting).

Which statement(s) is/are true about attack and release times?

• If the attack time is too fast, it can cause pumping.

• If the release time is too fast, it can cause pumping.

• If the attack time is too slow, it can cause lagging.

• If the release time is too slow, it can cause lagging.

Answer explanation

Both of these issues are result of not setting the correct attack time.

Which compressions scheme(s) use(s) input compression?

• Compression Limiting

• WDRC

• Comfort-Controlled Compression

• Syllabic Compression.

Answer explanation

Compression Limiting is a type of output compression.

Which compression scheme(s) use(s) low compression thresholds (e.g., 50 dB SPL)?

• Compression Limiting

• WDRC

• Comfort-Controlled Compression

• Syllabic Compression

Answer explanation

Compression Limiting uses a high compression threshold. Comfort-Controlled Compression uses a moderate compression threshold.