The role of high-CF fibers in speech perception: Comments on Horwitz et al. (2002) (L)

In a recent paper, Horwitz et al. [J. Acoust. Soc. Am. 111, 409-416 (2002)] concluded that listeners with high-frequency hearing impairment show a decrement in the perception of low-frequency speech sounds that is due to loss of information normally carried by auditory-nerve fibers with high characteristic frequencies (CFs). However, in their own study and in other studies, highpass-filtered noise did not degrade the perception of lowpass-filtered speech in listeners with normal hearing. An alternate conclusion proposed by Strickland et al. [J. Acoust. Soc. Am. 95, 497-501 (1994)] is that information conveyed by high-CF fibers is not necessary for speech perception. To reconcile these opposite conclusions, we suggest that the hearing-impaired listeners tested by Horwitz et al. may not have had normal hearing even in the low frequencies, and that the conclusion from Strickland et al. remains correct: high-CF fibers are not necessary for normal speech perception.