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.

The HiResolution Bionic Ear has the ability to steer current through simultaneous stimulation of adjacent electrode contacts. These data show that the majority of subjects perceive additional spectral channels other than those associated with stimulation of the fixed electrodes when current steering is implemented. The results suggest that the average cochlear implant user may have significantly more place-pitch capability than is exploited presently by cochlear implant systems. Current steering will be implemented in a wearable sound-processing strategy that can deliver up to 120 spectral channels to CII and HiRes 90K recipients. The new strategy takes advantage of untapped capabilities of the CII/HiRes 90K implanted electronics and will be implemented through software, with no additional surgery required. It is anticipated that the improved spectral resolution offered by current steering will lead to better speech perception in noise and improved music appreciation.

Objective: This study compared speech perception benefits in adults implanted with the HiResolution^TM (HiRes) Bionic Ear who used both conventional and HiRes sound processing. A battery of speech tests was used to determine which formats were most appropriate for documenting the wide range of benefit experienced by cochlear-implant users. Study Design: A repeated-measures design was used to assess postimplantation speech perception in adults who received the HiResolution Bionic Ear in a recent clinical trial. Patients were fit first with conventional strategies and assessed after 3 months of use. Patients were then switched to HiRes sound processing and assessed again after 3 months of use. To assess the immediate effect of HiRes sound processing on speech perception performance, consonant recognition testing was performed in a subset of patients after 3 days of HiRes use and compared with their 3-month performance with conventional processing. Setting: Subjects were implanted and evaluated at 19 cochlear implant programs in the USA and Canada affiliated primarily with tertiary medical centers. Patients: Patients were 51 postlinguistically deafened adults. Main Outcome Measures: Speech perception was assessed using CNC monosyllabic words, CID sentences and HINT sentences in quiet and noise. Consonant recognition testing was also administered to a subset of patients (n = 30) using the Iowa Consonant Test presented in quiet and noise. All patients completed a strategy preference questionnaire after 6 months of device use. Results: Consonant identification in quiet and noise improved significantly after only 3 days of HiRes use. The mean improvement from conventional to HiRes processing was significant on all speech perception tests. The largest differences occurred for the HINT sentences in noise. Ninety-six percent of the patients preferred HiRes to conventional sound processing. Ceiling effects occurred for both sentence tests in quiet. Conclusions: Although most patients improved after switching to HiRes sound processing, the greatest differences were seen in the ‘poor’ performers because ‘good’ performers often reached ceiling performance, especially on tests in quiet. Future evaluations of cochlear-implant benefit should make use of more difficult measures, especially for ‘good’ users. Nonetheless, a range of difficulty must remain in test materials to document benefit in the entire population of implant recipients.

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