More hearing aid compression channels measurably degrade vowel perception in hearing-impaired listeners.

Evidence

Bor, Souza, and Wright (2008) made acoustic and perceptual measurements and noted that the spectral contrast present in vowels decreased with increasing number of compression channels. Furthermore, perception of the vowels degraded as well. Listeners with hearing loss made more vowel confusions as the number of channels increased. Performance was poorest for 16 channels, and relatively unchanged between 1 and 8 channels. The implications for these results are many, as vowel stimuli are not the only speech sounds that require the presence of spectral contrast. Other sounds, such as fricatives and musical notes produced by different instruments, may also be particularly susceptible to multichannel WDRC algorithms. Yet, note that some studies have not demonstrated a negative relationship between number of channels and speech perception, even in noise (e.g., Yund & Buckles, 1995). Such results suggest that our ability to perceive speech may be very robust even in the presence of acoustic distortion. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1730

Bor, Souza, and Wright (2008) made acoustic and perceptual measurements and noted that the spectral contrast present in vowels decreased with increasing number of compression channels. Furthermore, perception of the vowels degraded as well. Listeners with hearing loss made more vowel confusions as the number of channels increased. Performance was poorest for 16 channels, and relatively unchanged between 1 and 8 channels. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1730

Categorization

• QUESTION: Worth chasing: why does performance plateau between 1-8 channels but collapse at 16? What threshold in channel count triggers the worst spectral flattening?
• XREF: Tension between this channel-count finding and the design goals of cochlear implants and multi-band compressors, where more channels are usually assumed better.
• corroborated: 2 independent passages support this claim — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1730