Digital Signal Processing in Hearing Aids Flashcards

What is the primary advantage of a multi-band compression system over single-band compression in hearing aids?

Answer: It allows independent gain adjustments across different frequency regions

Multi-band compression processes each frequency region independently, allowing precise gain fitting that matches the audiogram across frequencies.

In DSP hearing aids, what does the term 'attack time' refer to in dynamic range compression?

Answer: The time for the compressor to respond to a sudden loud sound

Attack time is how quickly the compression circuit reduces gain after detecting a sound that exceeds the compression threshold.

Which sampling rate is most commonly used in modern digital hearing aids?

Answer: 32 kHz

Most modern hearing aids sample at approximately 32 kHz, providing adequate bandwidth for speech and environmental sounds while managing power consumption.

What is 'spectral subtraction' used for in digital hearing aid processing?

Answer: Noise reduction by estimating and removing steady-state background noise

Spectral subtraction estimates the noise spectrum during quiet pauses and subtracts it from the incoming signal to reduce steady-state background noise.

A patient reports that their hearing aid makes speech sound 'tinny' or metallic. Which DSP parameter adjustment would most likely address this complaint?

Answer: Boosting low-frequency gain or reducing high-frequency emphasis

A tinny or metallic sound perception typically indicates excessive high-frequency gain or insufficient low-frequency energy, which can be corrected by adjusting the frequency shaping.

What is the function of a 'notch filter' in digital hearing aid feedback management?

Answer: It attenuates a narrow frequency band where feedback oscillation occurs

A notch filter targets and attenuates the specific frequency at which feedback whistling is occurring, eliminating the oscillation.

In hearing aid DSP, 'binaural coordination' between two hearing aids most commonly uses which wireless protocol?

Answer: Near Field Magnetic Induction (NFMI) or Bluetooth Low Energy

Most modern binaural hearing aid systems use NFMI or Bluetooth Low Energy (BLE) to wirelessly synchronize processing between the two devices.