The relative phonetic contributions of a cochlear implant and residual acoustic hearing to bimodal speech perception.
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ABSTRACT:
SUBMITTER: Sheffield BM
PROVIDER: S-EPMC3283905 | biostudies-other | 2012 Jan
REPOSITORIES: biostudies-other
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Project description:While outcomes with cochlear implants (CIs) are generally good, performance can be fragile. The authors examined two factors that are crucial for good CI performance. First, while there is a clear benefit for adding residual acoustic hearing to CI stimulation (typically in low frequencies), it is unclear whether this contributes directly to phonetic categorization. Thus, the authors examined perception of voicing (which uses low-frequency acoustic cues) and fricative place of articulation (s/?, which does not) in CI users with and without residual acoustic hearing. Second, in speech categorization experiments, CI users typically show shallower identification functions. These are typically interpreted as deriving from noisy encoding of the signal. However, psycholinguistic work suggests shallow slopes may also be a useful way to adapt to uncertainty. The authors thus employed an eye-tracking paradigm to examine this in CI users.Participants were 30 CI users (with a variety of configurations) and 22 age-matched normal hearing (NH) controls. Participants heard tokens from six b/p and six s/? continua (eight steps) spanning real words (e.g., beach/peach, sip/ship). Participants selected the picture corresponding to the word they heard from a screen containing four items (a b-, p-, s- and ?-initial item). Eye movements to each object were monitored as a measure of how strongly they were considering each interpretation in the moments leading up to their final percept.Mouse-click results (analogous to phoneme identification) for voicing showed a shallower slope for CI users than NH listeners, but no differences between CI users with and without residual acoustic hearing. For fricatives, CI users also showed a shallower slope, but unexpectedly, acoustic + electric listeners showed an even shallower slope. Eye movements showed a gradient response to fine-grained acoustic differences for all listeners. Even considering only trials in which a participant clicked "b" (for example), and accounting for variation in the category boundary, participants made more looks to the competitor ("p") as the voice onset time neared the boundary. CI users showed a similar pattern, but looked to the competitor more than NH listeners, and this was not different at different continuum steps.Residual acoustic hearing did not improve voicing categorization suggesting it may not help identify these phonetic cues. The fact that acoustic + electric users showed poorer performance on fricatives was unexpected as they usually show a benefit in standardized perception measures, and as sibilants contain little energy in the low-frequency (acoustic) range. The authors hypothesize that these listeners may overweight acoustic input, and have problems when this is not available (in fricatives). Thus, the benefit (or cost) of acoustic hearing for phonetic categorization may be complex. Eye movements suggest that in both CI and NH listeners, phoneme categorization is not a process of mapping continuous cues to discrete categories. Rather listeners preserve gradiency as a way to deal with uncertainty. CI listeners appear to adapt to their implant (in part) by amplifying competitor activation to preserve their flexibility in the face of potential misperceptions.
| S-EPMC4717908 | biostudies-literature
Project description:The purpose of this project was to evaluate differences between groups and device configurations for emotional responses to non-speech sounds. Three groups of adults participated: 1) listeners with normal hearing with no history of device use, 2) hearing aid candidates with or without hearing aid experience, and 3) bimodal cochlear-implant listeners with at least 6 months of implant use. Participants (n = 18 in each group) rated valence and arousal of pleasant, neutral, and unpleasant non-speech sounds. Listeners with normal hearing rated sounds without hearing devices. Hearing aid candidates rated sounds while using one or two hearing aids. Bimodal cochlear-implant listeners rated sounds while using a hearing aid alone, a cochlear implant alone, or the hearing aid and cochlear implant simultaneously. Analysis revealed significant differences between groups in ratings of pleasant and unpleasant stimuli; ratings from hearing aid candidates and bimodal cochlear-implant listeners were less extreme (less pleasant and less unpleasant) than were ratings from listeners with normal hearing. Hearing aid candidates' ratings were similar with one and two hearing aids. Bimodal cochlear-implant listeners' ratings of valence were higher (more pleasant) in the configuration without a hearing aid (implant only) than in the two configurations with a hearing aid (alone or with an implant). These data support the need for further investigation into hearing device optimization to improve emotional responses to non-speech sounds for adults with hearing loss.
| S-EPMC9019384 | biostudies-literature
Project description:The goals of the present study were to measure acoustic temporal modulation transfer functions (TMTFs) in cochlear implant listeners and examine the relationship between modulation detection and speech recognition abilities. The effects of automatic gain control, presentation level and number of channels on modulation detection thresholds (MDTs) were examined using the listeners' clinical sound processor. The general form of the TMTF was low-pass, consistent with previous studies. The operation of automatic gain control had no effect on MDTs when the stimuli were presented at 65 dBA. MDTs were not dependent on the presentation levels (ranging from 50 to 75 dBA) nor on the number of channels. Significant correlations were found between MDTs and speech recognition scores. The rates of decay of the TMTFs were predictive of speech recognition abilities. Spectral-ripple discrimination was evaluated to examine the relationship between temporal and spectral envelope sensitivities. No correlations were found between the two measures, and 56% of the variance in speech recognition was predicted jointly by the two tasks. The present study suggests that temporal modulation detection measured with the sound processor can serve as a useful measure of the ability of clinical sound processing strategies to deliver clinically pertinent temporal information.
| S-EPMC3155593 | biostudies-other
Project description:The aim of this study was to assess the frequency-position function resulting from electric stimulation of electrodes in cochlear implant subjects with significant residual hearing in their nonimplanted ear. Six cochlear implant users compared the pitch of the auditory sensation produced by stimulation of an intracochlear electrode to the pitch of acoustic pure tones presented to their contralateral nonimplanted ear. Subjects were implanted with different Clarion electrode arrays, designed to lie close to the inner wall of the cochlea. High-resolution radiographs were used to determine the electrode positions in the cochlea. Four out of six subjects presented electrode insertions deeper than 450 degrees . We used a two-interval (one acoustic, one electric), two-alternative forced choice protocol (2I-2AFC), asking the subject to indicate which stimulus sounded the highest in pitch. Pure tones were used as acoustic stimuli. Electric stimuli consisted of trains of biphasic pulses presented at relatively high rates [higher than 700 pulses per second (pps)]. First, all electric stimuli were balanced in loudness across electrodes. Second, acoustic pure tones, chosen to approximate roughly the pitch sensation produced by each electrode, were balanced in loudness to electric stimuli. When electrode insertion lengths were used to describe electrode positions, the pitch sensations produced by electric stimulation were found to be more than two octaves lower than predicted by Greenwood's frequency-position function. When insertion angles were used to describe electrode positions, the pitch sensations were found about one octave lower than the frequency-position function of a normal ear. The difference found between both descriptions is because of the fact that these electrode arrays were designed to lie close to the modiolus. As a consequence, the site of excitation produced at the level of the organ of Corti corresponds to a longer length than the electrode insertion length, which is used in Greenwood's function. Although exact measurements of the round window position as well as the length of the cochlea could explain the remaining one octave difference found when insertion angles were used, physiological phenomena (e.g., stimulation of the spiral ganglion cells) could also create this difference. From these data, analysis filters could be determined in sound coding strategies to match the pitch percepts elicited by electrode stimulation. This step might be of main importance for music perception and for the fitting of bilateral cochlear implants.
| S-EPMC2504582 | biostudies-other
Project description:Purpose:There is a growing interest in speech intelligibility and auditory perception of deaf children. The aim of the present study was to compare speech intelligibility and auditory perception of pre-school children with Hearing Aid (HA), Cochlear Implant (CI), and Typical Hearing (TH). Methods:The research design was descriptive-analytic and comparative. The participants comprised 75 male pre-school children aged 4-6 years in the 2017-2018 from Tehran, Iran. The participants were divided into three groups, and each group consisted of 25 children. The first and second groups were respectively selected from pre-school children with HA and CI using the convenience sampling method, while the third group was selected from pre-school children with TH by random sampling method. All children completed Speech Intelligibility Rating and Categories of Auditory Performance Questionnaires. Results:The findings indicated that the mean scores of speech intelligibility and auditory perception of the group with TH were significantly higher than those of the other groups (P < 0.0001). The mean scores of speech intelligibility in the group with CI did not significantly differ from those of the group with HA (P < 0.38). Also, the mean scores of auditory perception in the group with CI were significantly higher than those of the group with HA (P < 0.002). Conclusion:The results showed that auditory perception in children with CI was significantly higher than children with HA. This finding highlights the importance of cochlear implantation at a younger age and its significant impact on auditory perception in deaf children.
| S-EPMC7231984 | biostudies-literature
Project description:Clinical speech perception tests with simple presentation conditions often overestimate the impact of signal preprocessing on speech perception in complex listening environments. A new procedure was developed to assess speech perception in interleaved acoustic environments of different complexity that allows investigation of the impact of an automatic scene classification (ASC) algorithm on speech perception. The procedure was applied in cohorts of normal hearing (NH) controls and uni- and bilateral cochlear implant (CI) users. Speech reception thresholds (SRTs) were measured by means of a matrix sentence test in five acoustic environments that included different noise conditions (amplitude modulated and continuous), two spatial configurations, and reverberation. The acoustic environments were encapsulated in a randomized, mixed order single experimental run. Acoustic room simulation was played back with a loudspeaker auralization setup with 128 loudspeakers. 18 NH, 16 unilateral, and 16 bilateral CI users participated. SRTs were evaluated for each individual acoustic environment and as mean-SRT. Mean-SRTs improved by 2.4 dB signal-to-noise ratio for unilateral and 1.3 dB signal-to-noise ratio for bilateral CI users with activated ASC. Without ASC, the mean-SRT of bilateral CI users was 3.7 dB better than the SRT of unilateral CI users. The mean-SRT indicated significant differences, with NH group performing best and unilateral CI users performing worse with a difference of up to 13 dB compared to NH. The proposed speech test procedure successfully demonstrated that speech perception and benefit with ASC depend on the acoustic environment.
| S-EPMC8150447 | biostudies-literature
Project description:Many cochlear implant users with binaural residual (acoustic) hearing benefit from combining electric and acoustic stimulation (EAS) in the implanted ear with acoustic amplification in the other. These bimodal EAS listeners can potentially use low-frequency binaural cues to localize sounds. However, their hearing is generally asymmetric for mid- and high-frequency sounds, perturbing or even abolishing binaural cues. Here, we investigated the effect of a frequency-dependent binaural asymmetry in hearing thresholds on sound localization by seven bimodal EAS listeners. Frequency dependence was probed by presenting sounds with power in low-, mid-, high-, or mid-to-high-frequency bands. Frequency-dependent hearing asymmetry was present in the bimodal EAS listening condition (when using both devices) but was also induced by independently switching devices on or off. Using both devices, hearing was near symmetric for low frequencies, asymmetric for mid frequencies with better hearing thresholds in the implanted ear, and monaural for high frequencies with no hearing in the non-implanted ear. Results show that sound-localization performance was poor in general. Typically, localization was strongly biased toward the better hearing ear. We observed that hearing asymmetry was a good predictor for these biases. Notably, even when hearing was symmetric a preferential bias toward the ear using the hearing aid was revealed. We discuss how frequency dependence of any hearing asymmetry may lead to binaural cues that are spatially inconsistent as the spectrum of a sound changes. We speculate that this inconsistency may prevent accurate sound-localization even after long-term exposure to the hearing asymmetry.
| S-EPMC9829999 | biostudies-literature
Project description:Introduction and objectivesAmong cochlear implant candidates, an increasing number of patients are presenting with residual acoustic hearing. To monitor the postoperative course of structural and functional preservation of the cochlea, a reliable objective biomarker would be desirable. Recently, impedance telemetry has gained increasing attention in this field. The aim of this study was to investigate the postoperative course of the residual acoustic hearing and clinical impedance in patients with long electrode arrays and to explore the applicability of impedance telemetry for monitoring residual hearing.MethodsWe retrospectively analyzed records of 42 cochlear implant recipients with residual hearing covering a median postoperative follow-up of 25 months with repeated simultaneous pure tone audiometry and impedance telemetry. We used a linear mixed-effects model to estimate the relation between clinical electrode impedance and residual hearing. Besides the clinical impedance, the follow-up time, side of implantation, gender, and age at implantation were included as fixed effects. An interaction term between impedance and follow-up time, as well as subject-level random intercepts and slopes, were included.ResultsLoss of residual hearing occurred either during surgery or within the first 6 post-operative months. Electrode contacts inserted further apically (i.e., deeper) had higher impedances, independent of residual hearing. The highest impedances were measured 1 month postoperatively and gradually decreased over time. Basal electrodes were more likely to maintain higher impedance. Follow-up time was significantly associated with residual hearing. Regardless of the time, we found that a 1 kΩ increase in clinical impedance was associated with a 4.4 dB deterioration of residual hearing (p < 0.001).ConclusionPure tone audiometry is the current gold standard for monitoring postoperative residual hearing. However, the association of clinical impedances with residual hearing thresholds found in our study could potentially be exploited for objective monitoring using impedance telemetry. Further analysis including near-field related impedance components could be performed for improved specificity to local immune responses.
| S-EPMC9271767 | biostudies-literature
Project description:ObjectivesThe primary objective of this study is to identify the biographic, audiologic, and electrode position factors that influence speech perception performance in adult cochlear implant (CI) recipients implanted with a device from a single manufacturer. The secondary objective is to investigate the independent association of the type of electrode (precurved or straight) with speech perception.DesignIn a cross-sectional study design, speech perception measures and ultrahigh-resolution computed tomography scans were performed in 129 experienced CI recipients with a postlingual onset of hearing loss. Data were collected between December 2016 and January 2018 in the Radboud University Medical Center, Nijmegen, the Netherlands. The participants received either a precurved electrode (N = 85) or a straight electrode (N = 44), all from the same manufacturer. The biographic variables evaluated were age at implantation, level of education, and years of hearing loss. The audiometric factors explored were preoperative and postoperative pure-tone average residual hearing and preoperative speech perception score. The electrode position factors analyzed, as measured from images obtained with the ultrahigh-resolution computed tomography scan, were the scalar location, angular insertion depth of the basal and apical electrode contacts, and the wrapping factor (i.e., electrode-to-modiolus distance), as well as the type of electrode used. These 11 variables were tested for their effect on three speech perception outcomes: consonant-vowel-consonant words in quiet tests at 50 dB SPL (CVC50) and 65 dB SPL (CVC65), and the digits-in-noise test.ResultsA lower age at implantation was correlated with a higher CVC50 phoneme score in the straight electrode group. Other biographic variables did not correlate with speech perception. Furthermore, participants implanted with a precurved electrode and who had poor preoperative hearing thresholds performed better in all speech perception outcomes than the participants implanted with a straight electrode and relatively better preoperative hearing thresholds. After correcting for biographic factors, audiometric variables, and scalar location, we showed that the precurved electrode led to an 11.8 percentage points (95% confidence interval: 1.4-20.4%; p = 0.03) higher perception score for the CVC50 phonemes compared with the straight electrode. Furthermore, contrary to our initial expectations, the preservation of residual hearing with the straight electrode was poor, as the median preoperative and the postoperative residual hearing thresholds for the straight electrode were 88 and 122 dB, respectively.ConclusionsCochlear implantation with a precurved electrode results in a significantly higher speech perception outcome, independent of biographic factors, audiometric factors, and scalar location.
| S-EPMC8221708 | biostudies-literature
Project description:Spectrotemporal modulation (STM) detection performance was examined for cochlear implant (CI) users. The test involved discriminating between an unmodulated steady noise and a modulated stimulus. The modulated stimulus presents frequency modulation patterns that change in frequency over time. In order to examine STM detection performance for different modulation conditions, two different temporal modulation rates (5 and 10 Hz) and three different spectral modulation densities (0.5, 1.0, and 2.0 cycles/octave) were employed, producing a total 6 different STM stimulus conditions. In order to explore how electric hearing constrains STM sensitivity for CI users differently from acoustic hearing, normal-hearing (NH) and hearing-impaired (HI) listeners were also tested on the same tasks. STM detection performance was best in NH subjects, followed by HI subjects. On average, CI subjects showed poorest performance, but some CI subjects showed high levels of STM detection performance that was comparable to acoustic hearing. Significant correlations were found between STM detection performance and speech identification performance in quiet and in noise. In order to understand the relative contribution of spectral and temporal modulation cues to speech perception abilities for CI users, spectral and temporal modulation detection was performed separately and related to STM detection and speech perception performance. The results suggest that that slow spectral modulation rather than slow temporal modulation may be important for determining speech perception capabilities for CI users. Lastly, test-retest reliability for STM detection was good with no learning. The present study demonstrates that STM detection may be a useful tool to evaluate the ability of CI sound processing strategies to deliver clinically pertinent acoustic modulation information.
| S-EPMC4617902 | biostudies-literature