Biomedical subjects
Publications and source records attributed to S W Howe.
Cochlear implantation to restore some of the hearing in the profound or totally cochlear deaf patient has been briefly presented. An approximate two year follow up has not shown any complications. The Nucleus 22 channel cochlear implant, as presently manufactured, is a very useful device to rehabilitate profoundly or totally cochlear deaf patients.
The purpose of this study was to compare adult stutterers' and adult nonstutterers' fluent speech patterns produced during one nonshadowed reading and two speech shadowing conditions. Subjects' speech error rates, shadowing strategies, and fluent speech segment durations were obtained during baseline, diotic speech shadowing, and dichotic speech shadowing conditions. Results indicated that stutterers produced fewer speech production errors (i.e., omissions, substitutions, and insertions) than nonstutterers during each shadowing condition. Stutterers also favored the use of a word-by-word speech shadowing strategy, while nonstutterers utilized both word-by-word and small phrase shadowing strategies. Finally, stutterers exhibited significantly longer vowel and phrase durations than nonstutterers during the shadowing conditions.
Electrophysiological measures of the brainstem response to auditory stimuli permit comparisons to be made between latency shifts across intensity increments and psychophysical measures of loudness growth. Monaural comparisons leave much room for uncertainty in the interpretation of the nature of the relationship between the two response modes. A more definitive method for examining this relationship is to compare the monaural and binaural data obtained from psychophysical and electrophysiological measures. It is shown here that, while the brainstem electrophysiological response to intensity changes can be described by a power function, the latency of the neural response does not provide a direct link to the process of loudness summation or to the psychophysical response to loudness growth.
Recent research has associated long-standing conductive hearing losses and changes in brainstem neural responses. Investigations on human subjects to date have used behavioral modes in evaluating response changes for both short-term (induced) and long-term conductive losses. The present study measured brainstem electrical responses (BSERs) from 30 normally hearing adults divided into unilateral-induced conductive-loss groups of 10, 20 and 30 h. This auditory deprivation produced a significant decrease in the wave-I latency (auditory nerve response) across all groups. It is concluded that short-term auditory deprivation can result in VIII nerve fiber hyper-excitability when initially stimulated after the deprivation period. The occurrence of temporary changes under very short-term deprivation raises the possibility that alterations to brainstem neural responses may also be measurable electrophysiologically in individuals with long-term conductive losses, such as children with otitis media.
A recently developed technique to demonstrate binaural interaction in brainstem auditory electrical responses was systematically investigated. From analysis of the BSERs of eight normal hearing adults, it was found that variations in binaural interaction difference traces are related to an artificial relationship created by this technique between the true binaural and summed monaural waveforms. The present investigation employed a refinement of the binaural interaction technique whereby left and right monaural waveforms were subtracted individually from the binaural waveform to produce a difference trace. Analysis revealed that variations in the difference trace morphology are related to dependence of binaural latencies on left or right auditory tract preference in the brainstem auditory pathways. Within the subject population, 50% demonstrated an auditory tract preference for binaural latencies while 50% showed no preference. It was concluded that the difference trace is mathematically predictable from the morphological differences between the binaural and monaural waveforms and that a more accurate representation of binaural interaction can be obtained from a comparison of individual monaural waveforms within the binaural trace.