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Purpose: Speech perception in participants with auditory neuropathy (AN) was systematically studied to answer the following 2 questions: Does noise present a particular problem for people with AN? Can clear speech and cochlear implants alleviate this problem?
Method: The researchers evaluated the advantage in intelligibility of clear speech over conversational speech in 13 participants with AN. Of these participants, 7 had received a cochlear implant. Eight sentence-recognition experiments were conducted to examine the clear speech advantage in 2 listening conditions (quiet and noise) using 4 stimulation modes (monaural acoustic, diotic acoustic, monaural electric, and binaurally combined acoustic and electric stimulation).
Results: Participants with AN performed more poorly in speech recognition in noise than did the normal-hearing, cochlear-impaired, and cochlear implant controls. A significant clear speech advantage was observed, ranging from 9 to 23 percentage points in intelligibility for all listening conditions and stimulation modes. Electric stimulation via a cochlear implant produced significantly higher intelligibility than acoustic stimulation in both quiet and in noise. Binaural hearing with either diotic acoustic stimulation or combined acoustic and electric stimulation produced significantly higher intelligibility than monaural stimulation in quiet but not in noise.
Conclusions: Participants with AN most likely derive the clear speech advantage from enhanced temporal properties in clear speech and improved neural synchrony with electric stimulation. Although the present result supports cochlear implantation as one treatment choice for people with AN, it suggests that the use of innovative hearing aids may be another viable option to improve speech perception in noise.
KEY WORDS: auditory neuropathy, binaural hearing, clear speech, cochlear implant, speech perception
Hearing loss can be classified by conductive versus sensorineural loss or peripheral versus central processing disorders. These different types of hearing loss produce different perceptual consequences and may require different treatment strategies for optimal performance. Auditory neuropathy (AN) is a recently described hearing disorder that has unique pathologies and perceptual consequences (Starr et al., 1991, 2003; Starr, Picton, Sininger, Hood, & Berlin, 1996). One main characteristic of AN is the disrupted auditory nerve activity with concurrently normal or nearly normal cochlear amplification function. Clinically, the disrupted auditory nerve activity is reflected by highly distorted or absent auditory brainstem responses, whereas the normal cochlear amplification function is reflected by the presence ofotoacoustic emission and/or...