The case of a 51-year-old woman with an acoustic neuroma in her only hearing ear is presented. At the time the tumor was removed, May 24, 1979, a depth electrode was implanted In the cochlear nucleus. This worked for 2 months, allowing her to perceive sound in her environment. On March 12, 1981, the depth electrode was replaced with a surface electrode. Since that time her hearing has been as good as that of a patient with a cochlear implant. It has now been over 2 years since her last surgery and she continues to do well.

Four adult users of the House/3M single-channel cochlear implant were tested for their ability to label question and statement intonation contours (by auditory means alone) and to identify a set of 12 intervocalic consonants (with and without lipreading). Nineteen of 20 scores obtained on the question/statement task were significantly better than chance. Simplifying the stimulating waveform so as to signal fundamental frequency alone sometimes led to an improvement in performance. In consonant identification, lipreading alone scores were always far inferior to those obtained by lipreading with the implant. Phonetic feature analyses showed that the major effect of using the implant was to increase the transmission of voicing information, although improvements in the appropriate labelling of manner distinctions were also found. Place of articulation was poorly identified from the auditory signal alone. These results are best explained by supposing that subjects can use the relatively gross temporal information found in the stimulating waveforms (periodicity, randomness and silence) in a linguistic fashion. Amplitude envelope cues are of significant, but secondary, importance. By providing information that is relatively invisible, the House/3M device can thus serve as an important aid to lipreading, even though it relies primarily on the temporal structure of the stimulating waveform. All implant systems, including multi-channel ones, might benefit from the appropriate exploitation of such temporal features.

accurate physical three-dimensional reconstruction of the cochlear nuclear complex (CN), we used light microscopy to analyze the CN boundaries, cell types, and myelinated nerve bundles and transferred traced contours from enlarged photographs of serial sections onto acrylic plates. We produced two models, one demonstrating the CN in relation to the brain stem and the other showing the CN completely dissected out of the brain stem. The models localized the CN boundaries on the brain-stem surface and revealed topographic characteristics of the CN and a part of the eighth nerve adjacent to the brain stem. The major parts of the CN, namely, the ventral and dorsal cochlear nuclei, are located mainly within the lateral recess. The models produced are currently used in our institution to determine the optimal surgical and electrophysiologic approach to the CN. (Arch Otolaryngol 1985;111:495-501) It is well known that the cochlear nuclear complex (CN) is the first major relay center that processes information received through syn¬ apses with the cochlear nerve and then transmits it toward the cortex.The nuclei have been the subject of several intensive investigations that mainly studied carnivores1'7 and CA 90057 (Dr Terr). rodents.811 Primates, however, have received less attention, with only a few articles describing the CN in humans.1222The CN is a highly complicated heteromorphic formation consisting of several relatively well-separated divi¬ sions, namely, the dorsal (DCN) and ventral (VCN) cochlear nuclei, with smaller subdivisions of the latter.Although a part of the CN surface can be seen by the naked eye, gross analy¬ sis makes it difficult to appreciate the shape and dimensions of the cochlear nuclei in humans. The difficulty is due to the small size of the nuclei and the fact that the CN is almost completely hidden within the brain tissue and inseparable from it as a structural entity. At the same time, it may be equally difficult to understand the CN general spatial organization by study¬ ing individual or even serial histologie sections without specific reconstruc¬ tion methods. Three-dimensional re--· construction of the CN and the accu¬ rate characterization of the CN orien¬ tation have not been done yet. The morphology of the human CN is of substantial interest to us, since evaluation of the geometry of the nuclei is essential to further develop techniques for the electrical stimula¬ tion of the CN. Our institution cur¬ rently uses electrical stimulation of the cochlear nuclei as a form of rehabilitation of individuals deafened from the bilateral loss of the auditory nerves.23 MATERIALS AND METHODSTissue blocks were dissected from post¬ mortem, normal brains of adults. Macroexamination was completed on 20 brains. Detailed histologie examination was done on six brains (left and right sides). Varia¬ tions in the shape of the CN and adjacent structures, namely, root of the eighth nerve and inferior cerebellar peduncle, were not observed. One brain was utilized for three-dimensional reconstruction.The brai...

Clinicians have used speech stimuli when measuring the loudness discomfort level (LDL) to determine the upper intensity limit for test stimulus presentation, and to select the saturation sound pressure level for an individual's hearing aid. Because little research has investigated the effects of speech stimuli on the LDL, this study was undertaken to compare LDLs using six commercially available speech materials on 120 normally hearing listeners. Our comparisons showed no significant differences between the mean scores for any of the speech stimuli. These findings suggest that any differences in the mean LDLs among studies probably are not attributable to the speech stimuli. The intrasession reliability of LDL measurement was also assessed using a modified method of limits procedure with 2-dB increments and instructions stressing initial discomfort. It was concluded that examiners probably could attain a high degree of reliability by simply averaging the results of two ascending trials, because 95% of these test/retest differences did not exceed 6 dB. Our findings were integrated with previous studies in terms of: (1) test stimuli; (2) listener experience; (3) instructional set; and (4) psychophysical method. This discussion points to many unanswered questions and concludes that the LDL should be interpreted very cautiously. Moreover, it is suggested that the stimuli selected for LDL measurement should reflect the examiner's purpose.

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