Labeling of musical interval size by cochlear implant patients and normally hearing subjects.

OBJECTIVE: To compare the performance of cochlear implant patients and normal-hearing subjects on a musical interval labeling task, and to determine whether information regarding musical interval size is available to cochlear implant patients under realistic everyday listening conditions. DESIGN: Two Nucleus cochlear implant patients listened to musical intervals that consisted of systematic variations of electric pulse rate on single bipolar intracochlear electrode pairs, whereas normal-hearing listeners were presented with the acoustical analog of these stimuli. Subjects labeled the intonation quality of the stimulus intervals ("flat," "sharp," or "in tune"), relative to their memory for specific intervals abstracted from familiar melodies. The cochlear implant patients, in addition, performed this task with realistic acoustical musical stimuli. RESULTS: The interval labeling behavior of cochlear implant subjects, at low pulse rates, was similar to that of normal-hearing subjects. Furthermore, pitch interval information does not appear to be available to cochlear implant subjects when they are listening to acoustical stimuli via their speech processors. CONCLUSIONS: Temporal information appears to be sufficient for the perception of musical pitch. Encoding strategies that are highly successful in restoring speech understanding do not necessarily provide information regarding melodic pitch interval size.

Speech perception abilities of adult and pediatric Nucleus implant recipients using the Spectral Peak (SPEAK) coding strategy.

A series of 73 postlinguistically deafened adults and 34 prelinguistically deafened children were evaluated with the Spectral Peak (SPEAK) coding strategy of the Nucleus 22-channel cochlear implant. The adults who received consecutive implants demonstrated rapid acquisition of open-set speech recognition skills in the initial postoperative period. Group mean sentence recognition improved to 53.5% (n = 52) after 2 weeks, 62.1% (n = 55) after 1 month, 69.8% (n = 57) after 3 months, and 74.4% (n = 42) after 6 months of use. At the 6-month evaluation interval, 43% of subjects scored greater than 90% on sound-alone sentence recognition in quiet and only one patient (2.4%) scored less than 10%. Mean monosyllabic word recognition was 35.6% after 6 months of use. The 34 prelinguistically deafened children were converted from the Multipeak strategy to Spectral Peak strategy at four large pediatric implant centers. After 6 months of using the new coding strategy, the children demonstrated significant improvements in their speech perception abilities.

Pulse rate matching by cochlear implant patients: effects of loudness randomization and electrode position.

OBJECTIVE: To assess the accuracy with which cochlear implant patients are able to match two stimuli on the basis of pulse rate pitch. DESIGN: Patients were required to adjust the pulse rate of a comparison stimulus to match that of a fixed reference stimulus. The comparison and the reference stimuli differed in loudness or were presented to different electrodes. RESULTS: Patients were able to match stimuli on the basis of pulse rate, with varying degrees of accuracy. Deviations from the target and the amount of variability were greater when stimuli were presented to different electrodes. The results also provide evidence regarding level-dependent pitch shifts. CONCLUSIONS: Because of methodological limitations, conclusions regarding pitch equivalence are limited. However, patients vary significantly in their ability to utilize temporal information.

Musical pitch perception with pulsatile stimulation of single electrodes in patients implanted with the Nucleus cochlear implant.

Subjects implanted with a Nucleus cochlear implant participated in closed-set melody recognition and musical pitch experiments in which pitch was mediated by systematic changes in pulse rate on single intracochlear electrodes. The results suggest that temporal information is sufficient for musical interval perception.

Intonation of musical intervals by musical intervals by deaf subjects stimulated with single bipolar cochlear implant electrodes.

Some subjects with cochlear implants have been shown to associate electrical stimulus pulse rates with the pitches of musical tones. In order to clarify the role of these pitch sensations in a musical context, the present investigation examined the intonation accuracy achieved by implant subjects when adjusting pulse rates in the reconstruction of musical intervals. Using a method of adjustment, the subjects altered a variable pulse rate, relative to a fixed reference rate, on one electrode, in the tuning of musical intervals abstracted from familiar melodies. At low pulse rates, subjects generally tuned the intervals to the same frequency ratios which define tonal musical intervals in normal-hearing listeners, with error margins comparable to musically untrained subjects. Two subjects were, in addition, able to transpose these melodic intervals from a standard reference pulse rate to higher and lower reference rates (reference and target pulse rates with geometric means of the intervals ranging from 81 to 466 pulses/s). Generally, the intervals were adjusted on a ratio scale, according to the same frequency ratios which define analogous acoustical musical intervals. These results support the hypothesis that, at low pulse rates, a temporal code in the auditory nerve alone is capable of defining musical pitch.

Melody recognition and musical interval perception by deaf subjects stimulated with electrical pulse trains through single cochlear implant electrodes.

The perception of musical pitch was investigated in postlinguistically deaf subjects with cochlear implants. Stimuli consisted of sequences of biphasic electrical pulse trains at rates which represented the tones of the equal-tempered musical scale, delivered at equalized comfortable loudness levels to selected single bipolar electrodes along the array of the Nucleus cochlear implant. Seventeen subjects correctly identified a mean of 44% of rhythmically intact familiar tunes, presented in an open-set paradigm. Three subjects were tested with a closed set of melodies without rhythmic cues. The results showed relatively higher recognition scores at lower pulse rates, although melody recognition remained possible up to rates of approximately 600-800 pulses per second. Stimulation of apical electrodes yielded higher recognition scores than of basal electrodes. The perception of musical intervals, defined as frequency ratios between two trains of stimulus pulse rates, was investigated in an interval intonation labeling experiment, for intervals ranging from a minor 3rd to a major 6th. Within a range of low pulse rates, subjects defined the intervals mediated by electrical pulse rate by the same ratios which govern musical intervals of tonal frequencies in normal-hearing listeners. It may be concluded that temporal cues are sufficient for the mediation of musical pitch, at least for the lower half of the range of fundamental frequencies commonly used in music.

Audiologic results with the MSP/MPEAK and WSP/F0F1F2 processors and coding strategies for the nucleus cochlear implant.

Seven Nucleus, multichannel, cochlear-implant recipients underwent a 4-week trial with a Research Speech Processor (RSP). For five users of the Wearable Speech Processor (WSPIII), the RSP consisted of a Mini Speech Processor (MSP) with a MultiPeak (MPEAK) coding strategy, and for two MSP users, a WSPIII, utilizing an F0F1F2 coding strategy was used. Scores on an auditory-only, speech perception test battery were used to compare performance with each device. Patients were evaluated with their own processor before and after their RSP experience, to assess potential practice effects. In general, the patients with higher baseline scores appeared to be better able to take advantage of the additional information provided by the MSP/MPEAK combination.

Single-channel versus bilateral multichannel cochlear implant results: a case report.

Pre- and postoperative audiologic findings are compared in a patient who underwent three cochlear implant surgeries: an initial single-channel device in a recently deafened ear with no residual hearing, followed by a multichannel device in a congenitally deafened ear with a severe to profound loss, and subsequent explantation of the single-channel device and reimplantation with a multichannel device.

Audiologic findings in botulism poisoning.

Botulism poisoning results in a presynaptic failure of neuromuscular transmission, and may be expected to impair Eustachian tube and stapedius reflex function. The audiologic findings in five normal-hearing patients with type A botulism poisoning are presented. Results were varied. Two patients demonstrated type B or C tympanograms during the early stages, while three with normal middle ear function demonstrated marked bilateral or unilateral stapedius reflux threshold elevation. One patient had a reversible reflex decay, and the superimposition of a second stimulus upon the first resulted in complete recovery of reflex amplitude. A number of possible pathophysiological mechanisms are discussed.

The cochlear implant: a comparison of single-channel and multichannel results.

We have performed 39 cochlear implants at St. Paul's Hospital since 1982. Fourteen patients received a House/3M implant and 23 patients received a total of 25 multichannel Nucleus implants. We present a comparison of subjective and objective results in seven patients who first received a single channel implant and were subsequently implanted with a multichannel device. We also report in detail results obtained by a 55-year-old man who received a House/3M implant and subsequently received bilateral Nucleus implants. Results in this patient demonstrate some factors that influence successful use of an implant.

Cochlear implants: update of the program at the University of British Columbia.

Since 1982, we have performed 26 cochlear implants at the University of British Columbia. The first 14 patients were implanted with the House/3M single-channel unit and the last 12 have been implanted with the Nucleus 22-channel unit. This paper reviews the methods used in patient selection and rehabilitation and compares the results obtained in patients using a single-channel with those using a multi-channel unit.

Limitations of ABR as a hearing test as exemplified in multiply handicapped adults.

Some limitations of the audiometric application of the click-evoked ABR are exemplified in the results for this sample of multiply handicapped hearing-impaired adults. Normal ABR thresholds were not necessarily indicative of normal hearing. Complete absence of ABR was not necessarily associated with total deafness. These findings underscore the need for conservative interpretation when the ABR is used to assess hearing of neurologically impaired patients at risk for more central auditory dysfunction. Additional diagnostic information in problematic cases may be obtained with cortical auditory potentials. Electrophysiological data must, in turn, be integrated with behaviorally obtained results.

Cochlear implant experience at the University of British Columbia.

The authors review their experience with 13 totally deaf patients implanted with the House/3M cochlear implant. The preoperative evaluation, operative procedure, postoperative rehabilitation and hearing results are presented.

Management of tinnitus: a practical approach.

This paper presents our experience with 500 patients with intractable tinnitus who were referred to our tinnitus clinic during the past 10 years. We propose a management plan based on identification and classification of three types of tinnitus. We describe what a tinnitus clinic adds to patient care, with emphasis on how these treatment methods can be utilized in office practice.

Effects of click polarity on ABR peak latency and morphology in a clinical population.

Magnitude and direction of click phase-related shifts for ABR peaks I through V and the major interpeak intervals were measured for normal ears and ears with varying degrees of high frequency (HF) hearing loss. Latencies of Waves I and V were relatively stable with inversion of stimulus phase in ears with normal hearing and mild degrees of HF hearing loss, but the incidence of substantial phase-induced latency shifts increased in proportion to pure tone deficits. Waves II and IV demonstrated the greatest shifts in all hearing loss categories. Summation of dissimilar responses obtained with opposite acoustic polarities may result in response degradation. A number of phase-specific ABR abnormalities are discussed. In the greater proportion of ears, rarefaction clicks were the more productive stimulus in eliciting the full complement of response peaks.

The tuning fork--an essential instrument in otologic practice.

Two groups of people are critical of the tuning fork--those who have never used them and those who do not know how to use them. The tuning fork correctly used is still a dependable method of diagnosing conductive hearing loss and invaluable in the diagnosis of unilateral total sensorineural hearing loss. The degree of conductive loss can be estimated by using tuning forks of 256 through 1024 frequency. These statements are based on the results of this study in which tuning fork tests were performed on a series of patients who subsequently underwent complete otologic examination and audiometry. The method of tuning fork use, the value particularly in the diagnosis of conductive hearing loss, and the tuning fork's limitations are discussed.