Children with learning problems often cannot discriminate rapid acoustic changes that occur in speech. In this study of normal children and children with learning problems, impaired behavioral discrimination of a rapid speech change (/dalpha/versus/galpha/) was correlated with diminished magnitude of an electrophysiologic measure that is not dependent on attention or a voluntary response. The ability of children with learning problems to discriminate another rapid speech change (/balpha/versus/walpha/) also was reflected in the neurophysiology. These results indicate that some children's discrimination deficits originate in the auditory pathway before conscious perception and have implications for differential diagnosis and targeted therapeutic strategies for children with learning disabilities and attention disorders.

ABSTRACTthat underlie normal hearing. Auditory neuropathy is a hearing disorder in which peripheral hearing The neural representation of sensory events depends appears normal, but the eighth nerve and brainstem upon neural synchrony. Auditory neuropathy, a disorare abnormal (Davis and Hirsh 1979;; der of stimulus-timing-related neural synchrony, proStarr et al. 1991). By clinical definition, patients with vides a model for studying the role of synchrony in this disorder have normal otoacoustic emissions auditory perception. This article presents electrophysi-(OAEs) and cochlear microphonic (CM) potentials, ological and behavioral data from a rare case of audibut exhibit an absent or severely abnormal auditory tory neuropathy in a woman with normal hearing brainstem response (ABR) (Starr et al. 1996). Because thresholds, making it possible to separate audibility a normal ABR is recorded only when multiple neurons from neuropathy. The experimental results, which fire synchronously at stimulus onset, patients with audiencompass a wide range of auditory perceptual abilitory neuropathy provide an opportunity to examine ties and neurophysiologic responses to sound, provide the role of synchrony in perception. new information linking neural synchrony with audiThe electrophysiological tests for diagnosing auditory perception. Findings illustrate that optimal eighth tory neuropathy can be used in very young children, nerve and auditory brainstem synchrony do not allowing this disorder to be identified early in life. The appear to be essential for understanding speech in functional ramifications remain unclear, with reports quiet listening situations. However, synchrony is critiranging from functional deafness to relatively intact cal for understanding speech in the presence of noise.speech perception in quiet but severely impaired per-

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These results indicate that additional pitch percepts can be created using current steering.