Adjustments of the amplitude mapping function: Sensitivity of cochlear implant users and effects on subjective preference and speech recognition

Hoek, Femke L. Theelen–van den; Boymans, Monique; Dijk, Bas van; Dreschler, Wouter A.

doi:10.1080/14992027.2016.1202454

Cited by 4 publications

(3 citation statements)

References 27 publications

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“…However, usually the default settings are used in clinical practice and complete loudness growth functions are not measured to save measurement time. However, CI listeners are sensitive to changes in the mapping and it affects their loudness perception (Theelen-van den Hoek et al, 2016), and the best performance on speech perception is found when normal loudness growth is restored (Fu and Shannon, 1998).…”

Section: Introductionmentioning

confidence: 99%

Electrically-evoked auditory steady-state responses as neural correlates of loudness growth in cochlear implant users

2018

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Section: Introductionmentioning

confidence: 99%

Electrically-evoked auditory steady-state responses as neural correlates of loudness growth in cochlear implant users

2018

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“…Some fitting prescriptions aim for this [ 15 ]. Also, at the electrical side, there is evidence that lower intensities should be (almost) equally loud as higher intensities [ 16 , 17 ]. SCORE allows investigating the effect of alternative loudness targets.…”

Section: Introductionmentioning

confidence: 99%

Real-time loudness normalisation with combined cochlear implant and hearing aid stimulation

et al. 2018

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BackgroundPeople who use a cochlear implant together with a contralateral hearing aid—so-called bimodal listeners—have poor localisation abilities and sounds are often not balanced in loudness across ears. In order to address the latter, a loudness balancing algorithm was created, which equalises the loudness growth functions for the two ears. The algorithm uses loudness models in order to continuously adjust the two signals to loudness targets. Previous tests demonstrated improved binaural balance, improved localisation, and better speech intelligibility in quiet for soft phonemes. In those studies, however, all stimuli were preprocessed so spontaneous head movements and individual head-related transfer functions were not taken into account. Furthermore, the hearing aid processing was linear.Study designIn the present study, we simplified the acoustical loudness model and implemented the algorithm in a real-time system. We tested bimodal listeners on speech perception and on sound localisation, both in normal loudness growth configuration and in a configuration with a modified loudness growth function. We also used linear and compressive hearing aids.ResultsThe comparison between the original acoustical loudness model and the new simplified model showed loudness differences below 3% for almost all tested speech-like stimuli and levels. We found no effect of balancing the loudness growth across ears for speech perception ability in quiet and in noise. We found some small improvements in localisation performance. Further investigation with a larger sample size is required.

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“…The changing compression is central to MOC processing. It is known that different static compression values influence the SRT (e.g., Fu & Shannon 1998 ; Theelen-van den Hoek et al 2016 ). Here, compression in the STD processor (i.e., the value of parameter c in Eq.…”

Section: Discussionmentioning

confidence: 99%

Speech-in-Noise Recognition With More Realistic Implementations of a Binaural Cochlear-Implant Sound Coding Strategy Inspired by the Medial Olivocochlear Reflex

et al. 2020

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Objectives: Cochlear implant (CI) users continue to struggle understanding speech in noisy environments with current clinical devices. We have previously shown that this outcome can be improved by using binaural sound processors inspired by the medial olivocochlear (MOC) reflex, which involve dynamic (contralaterally controlled) rather than fixed compressive acoustic-to-electric maps. The present study aimed at investigating the potential additional benefits of using more realistic implementations of MOC processing. Design: Eight users of bilateral CIs and two users of unilateral CIs participated in the study. Speech reception thresholds (SRTs) for sentences in competition with steady state noise were measured in unilateral and bilateral listening modes. Stimuli were processed through two independently functioning sound processors (one per ear) with fixed compression, the current clinical standard (STD); the originally proposed MOC strategy with fast contralateral control of compression (MOC1); a MOC strategy with slower control of compression (MOC2); and a slower MOC strategy with comparatively greater contralateral inhibition in the lower-frequency than in the higher-frequency channels (MOC3). Performance with the four strategies was compared for multiple simulated spatial configurations of the speech and noise sources. Based on a previously published technical evaluation of these strategies, we hypothesized that SRTs would be overall better (lower) with the MOC3 strategy than with any of the other tested strategies. In addition, we hypothesized that the MOC3 strategy would be advantageous over the STD strategy in listening conditions and spatial configurations where the MOC1 strategy was not. Results: In unilateral listening and when the implant ear had the worse acoustic signal-to-noise ratio, the mean SRT was 4 dB worse for the MOC1 than for the STD strategy (as expected), but it became equal or better for the MOC2 or MOC3 strategies than for the STD strategy. In bilateral listening, mean SRTs were 1.6 dB better for the MOC3 strategy than for the STD strategy across all spatial configurations tested, including a condition with speech and noise sources colocated at front where the MOC1 strategy was slightly disadvantageous relative to the STD strategy. All strategies produced significantly better SRTs for spatially separated than for colocated speech and noise sources. A statistically significant binaural advantage (i.e., better mean SRTs across spatial configurations and participants in bilateral than in unilateral listening) was found for the MOC2 and MOC3 strategies but not for the STD or MOC1 strategies. Conclusions: Overall, performance was best with the MOC3 strategy, which maintained the benefits of the originally proposed MOC1 strategy over the STD strategy for spatially separated speech and noise sources and extended those benefits to additional spatial configurations. In addition, the MOC3 strate...

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Adjustments of the amplitude mapping function: Sensitivity of cochlear implant users and effects on subjective preference and speech recognition

Cited by 4 publications

References 27 publications

Electrically-evoked auditory steady-state responses as neural correlates of loudness growth in cochlear implant users

Electrically-evoked auditory steady-state responses as neural correlates of loudness growth in cochlear implant users

Real-time loudness normalisation with combined cochlear implant and hearing aid stimulation

Speech-in-Noise Recognition With More Realistic Implementations of a Binaural Cochlear-Implant Sound Coding Strategy Inspired by the Medial Olivocochlear Reflex

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