New processing strategies in cochlear implantation.

New strategies for representing acoustic information with multichannel cochlear implants have produced substantial improvements in speech recognition for implant users. This report reviews within-subject comparison of a new continuous interleaved sampling (CIS) strategy with a compressed analog (CA) strategy used in a standard clinical device. In general, the comparison show higher levels of open-set speech recognition with CIS for each of the 11 subjects studied. Data on the importance of the patients variable in determining outcomes with cochlear implants are presented. A brief description of another new strategy, the spectral maxima sound processor (SMSP) strategy is given as well as information on the availability of CIS in various implant systems.

Hearing preservation using the modified translabyrinthine approach.

Removal of an acoustic neuroma using the translabyrinthine approach has previously been considered "incompatible" with hearing preservation. By modifying the approach and preventing the loss of endolymph, we have successfully removed two intracanalicular acoustic neuromas that originated from the inferior vestibular nerves, and preserved serviceable hearing in the ears operated on. This report represents the preliminary findings using this particular technique in the management of intracanalicular acoustic neuromas.

Importance of patient and processor variables in determining outcomes with cochlear implants.

Within-subjects comparisons of processing strategies for cochlear implants are reviewed. Compressed analog strategies were compared to interleaved pulses strategies in tests with one group of 8 subjects, and to continuous interleaved sampling strategies in tests with another group of 11 subjects. The tests included open-set recognition of words and sentences. The results show that, while different strategies may produce quite different outcomes across subjects, individual performances with one processing strategy are significantly correlated with those of alternative strategies. These findings emphasize the importance of patient variables in determining outcomes across a variety of prosthesis designs.

Design and evaluation of a continuous interleaved sampling (CIS) processing strategy for multichannel cochlear implants.

Two approaches for representing speech information with multichannel cochlear prostheses are being compared in tests with implant patients. Included in these studies are the compressed analog (CA) approach of a standard clinical device and research processors utilizing continuous interleaved sampling (CIS). Initial studies have been completed with nine subjects, seven of whom were selected on the basis of excellent performance with the Ineraid clinical processor, and the remaining two for their relatively poor performance with the same device. The tests include open-set recognition of words and sentences. Every subject has obtained a higher score--or repeated a score of 100% correct--on every test when using a CIS processor. These results are discussed in terms of their implications for processor design.

Better speech recognition with cochlear implants.

HIGH levels of speech recognition have been achieved with a new sound processing strategy for multielectrode cochlear implants. A cochlear implant system consists of one or more implanted electrodes for direct electrical activation of the auditory nerve, an external speech processor that transforms a microphone input into stimuli for each electrode, and a transcutaneous (rf-link) or percutaneous (direct) connection between the processor and the electrodes. We report here the comparison of the new strategy and a standard clinical processor. The standard compressed analogue (CA) processor presented analogue waveforms simultaneously to all electrodes, whereas the new continuous interleaved sampling (CIS) strategy presented brief pulses to each electrode in a nonoverlapping sequence. Seven experienced implant users, selected for their excellent performance with the CA processor, participated as subjects. The new strategy produced large improvements in the scores of speech reception tests for all subjects. These results have important implications for the treatment of deafness and for minimal representations of speech at the auditory periphery.

Coding strategies for multichannel cochlear prostheses.

Comparisons of analog and pulsatile coding strategies for multichannel cochlear prostheses are reviewed. The results are related to design considerations for pediatric implants, including efficacy, safety, ease of fitting, and access to future improvements.

Modifying the translabyrinthine approach to preserve hearing during acoustic tumour surgery.

Removing an acoustic schwannoma using the translabyrinthine approach has previously been considered incompatible with hearing preservation. By modifying the approach and preventing the loss of endolymph, we have successfully removed an intracanalicular acoustic schwannoma, which originated from the inferior vestibular nerve, and preserved hearing in the operated ear. This report represents the preliminary findings using this particular technique in the management of an intracanalicular acoustic tumour.

Comparative studies of speech processing strategies for cochlear implants.

A wide variety of speech processing strategies for multichannel auditory prostheses were compared in studies of two patients implanted with the UCSF electrode array. Each strategy was evaluated using tests of vowel and consonant confusions, with and without lipreading. Included among the strategies were the compressed analog processor of the present UCSF/Storz prosthesis and a group of interleaved pulses processors in which the amplitudes of nonsimultaneous pulses code the spectral variations of speech. For these patients, each with indications of poor nerve survival, test scores were significantly higher with the interleaved pulses processors. We believe this superior performance was a result of 1. the substantial release from channel interactions provided by nonsimultaneous stimuli and 2. a fast enough rotation among the channels to support adequate temporal and spectral resolution of perceived speech sounds.