HAC Hearing Aid Anatomy & Components Flashcards

What does WDRC stand for in hearing aid technology?

Answer: Wide Dynamic Range Compression

Wide Dynamic Range Compression (WDRC) applies more gain for soft sounds and less gain for loud sounds, accommodating the reduced dynamic range typical of sensorineural hearing loss.

What is the compression knee point (threshold) in a hearing aid?

Answer: The input level at which compression begins to operate

The compression knee point is the input SPL above which the hearing aid begins reducing gain, transitioning from linear to compressive amplification.

What does OSPL90 (or SSPL90) measure in hearing aid specifications?

Answer: Maximum output sound pressure level with a 90 dB SPL input sweep

OSPL90 is the output sound pressure level curve measured across frequencies with a 90 dB SPL input, defining the hearing aid's maximum saturation output.

What is the primary role of the digital signal processor (DSP) chip in a modern hearing aid?

Answer: Process the electrical signal to apply amplification, noise reduction, feedback cancellation, and other features

The DSP chip performs all real-time digital processing including multi-channel amplification, noise reduction, feedback suppression, and feature management.

Which term describes the high-pitched squealing sound produced when amplified sound from the receiver re-enters the microphone?

Answer: Acoustic feedback

Acoustic feedback occurs when amplified sound leaks from the receiver back into the microphone, creating an uncontrolled positive gain loop that produces squealing.

How does a directional microphone system improve speech understanding in noise?

Answer: It attenuates sounds arriving from behind the listener to improve the speech-to-noise ratio

Directional microphone systems reduce amplification of sounds originating from the rear hemisphere, improving the signal-to-noise ratio when the user faces the speech source.