Pure tone discrimination with cochlear implants and filter-band spread

Abstract

For many cochlear implant (CI) users, frequency discrimination is still challenging. We studied the effect of frequency differences relative to the electrode frequency bands on pure tone discrimination. A single-center, prospective, controlled, psychoacoustic exploratory study was conducted in a tertiary university referral center. Thirty-four patients with Cochlear Ltd. and MED-EL CIs and 19 age-matched normal-hearing control subjects were included. Two sinusoidal tones were presented with varying frequency differences. The reference tone frequency was chosen according to the center frequency of basal or apical electrodes. Discrimination abilities were psychophysically measured in a three-interval, two-alternative, forced-choice procedure (3I-2AFC) for various CI electrodes. Hit rates were measured, particularly with respect to discrimination abilities at the corner frequency of the electrode frequency-bands. The mean rate of correct decision concerning pitch difference was about 60% for CI users and about 90% for the normal-hearing control group. In CI users, the difference limen was two semitones, while normal-hearing participants detected the difference of one semitone. No influence of the corner frequency of the CI electrodes was found. In CI users, pure tone discrimination seems to be independent of tone positions relative to the corner frequency of the electrode frequency-band. Differences of 2 semitones can be distinguished within one electrode.

Best frequencies and temporal delays are similar across the low-frequency regions of the guinea pig cochlea

“…1B) to map different stimulus frequencies to different electrodes. Notably, patients show superior low-frequency pitch discrimination if their implant provides temporal information [( 39 ), figure 2)], and a pitch-matching study on a cochlear implant recipient with good contralateral hearing suggested that the place of apical electrodes did not affect the perceived pitch ( 40 ). Given the present results, it does not seem unexpected that devices providing phase-locked stimulation to the apex perform better, because the normal cochlear apex lacks a mechanical place code.…”

Effect of Cochlear Implant Electrode Insertion Depth on Speech Perception Outcomes: A Systematic Review

“…Interestingly, insertion depths exceeding 720° are not associated with better hearing outcomes so far ( 51 ). This might be caused by technical limitations, since the lowest detectable frequency through the default settings of all tested audio processors is 70 Hz ( 52 ). However, it has to be considered that frequencies beyond 70 Hz likely do not influence speech perception outcomes since the speech frequency band ranges from 0.5 kHz to 4 kHz ( 53 ).…”

Biophysical aspects of auditory perception in patients with cochlear implants

“…Как пишут некоторые авторы, даже в многоканальных системах кохлеарной имплантации различение частоты является достаточно сложной задачей, что отражается на качестве слухового восприятия особенно в сложных акустических условиях [18]. Ввиду отсутствия механизма частотной селективности, обусловленного функцией НВК (наружных волосковых клеток), а также за счет широкой области растекания электриче-2023;22;6(127) ского тока различение высоты у пациентов с КИ значительно хуже, чем у людей с нормальным слухом.…”

“…L. Wagner с соавт. [18] изучили влияние различий в частотах относительно частотных полос отдельных электродов на распознавание чистого тона. Средняя частота правильного принятия решения относительно разницы высоты тона составила около 60% для пользователей КИ и около 90% для группы с нормальным слухом.…”

“…[21] сообщили, что дифференциальный порог по частоте у пользователей КИ варьировал от одного до восьми полутонов. Низкую разрешающую способность по частоте у пользователей КИ отмечают и другие авторы [18].…”