The Effect of Binaural Beamforming Technology on Speech Intelligibility in Bimodal Cochlear Implant Recipients.

Although the benefit of bimodal listening in cochlear implant users has been agreed on, speech comprehension remains a challenge in acoustically complex real-life environments due to reverberation and disturbing background noises. One way to additionally improve bimodal auditory performance is the use of directional microphones. The objective of this study was to investigate the effect of a binaural beamformer for bimodal cochlear implant (CI) users. This prospective study measured speech reception thresholds (SRT) in noise in a repeated-measures design that varied in listening modality for static and dynamic listening conditions. A significant improvement in SRT of 4.7 dB was found with the binaural beamformer switched on in the bimodal static listening condition. No significant improvement was found in the dynamic listening condition. We conclude that there is a clear additional advantage of the binaural beamformer in bimodal CI users for predictable/static listening conditions with frontal target speech and spatially separated noise sources.

Optimising the effect of noise reduction algorithm ClearVoice in cochlear implant users by increasing the maximum comfort levels.

OBJECTIVE: ClearVoice is a single-microphone noise reduction algorithm in Advanced Bionics cochlear implant(CI) systems with the aim to improve performance in background noise. The present study investigated a hypothesised increased effect of ClearVoice if combined with a structural increase of maximum comfort stimulation levels (M-levels) in the CI fitting. DESIGN: We tested performance with ClearVoice (Medium) in four conditions, defined by combined settings of ClearVoice off/on and with/without 5% increase of M-levels. The main outcome measures were the Acceptable Noise Level (ANL) and the speech reception threshold in continuous background noise (SRTn). STUDY SAMPLE: Participants were 16 experienced cochlear implant recipients with Advanced Bionics implants and a Naida Q70 processor. RESULTS: The ANL significantly improved by using either ClearVoice or an increase of M-levels. Combining both settings gave the largest improvement in ANL. For the SRTn, we found a small, but significant interaction between ClearVoice and an increase of M-levels, implying that ClearVoice improved speech understanding slightly, but only if combined with a 5% increase of M-levels. CONCLUSIONS: Optimal profit from ClearVoice is obtained if combined with a structural 5% increase of M-levels.

Effects of a transient noise reduction algorithm on speech intelligibility in noise, noise tolerance and perceived annoyance in cochlear implant users.

OBJECTIVE: To evaluate the validity and efficacy of a transient noise reduction algorithm (TNR) in cochlear implant processing and the interaction of TNR with a continuous noise reduction algorithm (CNR). DESIGN: We studied the effects of TNR and CNR on the perception of realistic sound samples with transients, using subjective ratings of annoyance, a speech-in-noise test and a noise tolerance test. STUDY SAMPLE: Participants were 16 experienced cochlear implant recipients wearing an Advanced Bionics Naida Q70 processor. RESULTS: CI users rated sounds with transients as moderately annoying. Annoyance was slightly, but significantly reduced by TNR. Transients caused a large decrease in speech intelligibility in noise and a moderate decrease in noise tolerance, measured on the Acceptable Noise Level test. The TNR had no significant effect on noise tolerance or on speech intelligibility in noise. The combined application of TNR and CNR did not result in interactions. CONCLUSIONS: The TNR algorithm was effective in reducing annoyance from transient sounds, but was not able to prevent a decreasing effect of transients on speech understanding in noise and noise tolerance. TNR did not reduce the beneficial effect of CNR on speech intelligibility in noise, but no cumulated improvement was found either.

Self-Adjustment of Upper Electrical Stimulation Levels in CI Programming and the Effect on Auditory Functioning.

OBJECTIVES: With current cochlear implants (CIs), CI recipients achieve good speech perception in quiet surroundings. However, in acoustically complex, real-life environments, speech comprehension remains difficult and sound quality often remains poor. It is, therefore, a challenge to program CIs for such environments in a clinic. The CI manufacturer Cochlear Ltd. recently introduced a remote control that enables CI recipients to alter the upper stimulation levels of their user programs themselves. In this concept, called remote assistant fitting (RAF), bass and treble controls can be adjusted by applying a tilt to emphasize either the low- or high-frequency C-levels, respectively. This concept of self-programming may be able to overcome limitations associated with fine-tuning the CI sound processor in a clinic. The aim of this study was to investigate to what extent CI recipients already accustomed to their clinically fitted program would adjust the settings in daily life if able to do so. Additionally, we studied the effects of these changes on auditory functioning in terms of speech intelligibility (in quiet and in noise), noise tolerance, and subjectively perceived speech perception and sound quality. DESIGN: Twenty-two experienced adult CI recipients (implant use >12 months) participated in this prospective clinical study, which used a within-subject repeated measures design. All participants had phoneme scores of ≥70% at 65 dB SPL in quiet conditions, and all used a Cochlear Nucleus CP810 sound processor. Auditory performance was tested by a speech-in-quiet test, a speech-in-noise test, an acceptable noise level test, and a questionnaire about perceived auditory functioning, that is, a speech and sound quality (SSQ-C) questionnaire. The first session consisted of a baseline test in which the participants used their own CI program and were instructed on how to use RAF. After the first session, participants used RAF for 3 weeks at home. After these 3 weeks, the participants returned to the clinic for auditory functioning tests with their self-adjusted programs and completed the SSQ-C. RESULTS: Fifteen participants (68%) adjusted their C-level frequency profile by more than 5 clinical levels for at least one electrode. Seven participants preferred a higher contribution of the high frequencies relative to the low frequencies, while five participants preferred more low-frequency stimulation. One-third of the participants adjusted the high and low frequencies equally, while some participants mainly used the overall volume to change their settings. Several parts of the SSQ-C questionnaire scores showed an improvement in perceived auditory functioning after the subjects used RAF. No significant change was found on the auditory functioning tests for speech-in-quiet, speech-in-noise, or acceptable noise level. CONCLUSIONS: In conclusion, the majority of experienced CI users made modest changes in the settings of their programs in various ways and were able to do so with the RAF. After altering the programs, the participants experienced an improvement in speech perception in quiet environments and improved perceived sound quality without compromising auditory performance. Therefore, it can be concluded that self-adjustment of CI settings is a useful and clinically applicable tool that may help CI recipients to improve perceived sound quality in their daily lives.

Evaluation of a wireless remote microphone in bimodal cochlear implant recipients.

OBJECTIVE: To evaluate the benefit of a wireless remote microphone (MM) for speech recognition in noise in bimodal adult cochlear implant (CI) users both in a test setting and in daily life. DESIGN: This prospective study measured speech reception thresholds in noise in a repeated measures design with factors including bimodal hearing and MM use. The participants also had a 3-week trial period at home with the MM. STUDY SAMPLE: Thirteen post-lingually deafened adult bimodal CI users. RESULTS: A significant improvement in SRT of 5.4 dB was found between the use of the CI with the MM and the use of the CI without the MM. By also pairing the MM to the hearing aid (HA) another improvement in SRT of 2.2 dB was found compared to the situation with the MM paired to the CI alone. In daily life, participants reported better speech perception for various challenging listening situations, when using the MM in the bimodal condition. CONCLUSION: There is a clear advantage of bimodal listening (CI and HA) compared to CI alone when applying advanced wireless remote microphone techniques to improve speech understanding in adult bimodal CI users.

Application of Noise Reduction Algorithm ClearVoice in Cochlear Implant Processing: Effects on Noise Tolerance and Speech Intelligibility in Noise in Relation to Spectral Resolution.

OBJECTIVES: Noise reduction algorithms have recently been introduced in the design of clinically available cochlear implants. This study was intended to (1) evaluate the effect of noise reduction algorithm "ClearVoice" on noise tolerance and on speech intelligibility in noisy conditions at different speech-in-noise ratios in cochlear implant users, and (2) test the hypothesis that CI recipients with low spectral resolution might benefit more from noise reduction algorithms than CI users with high spectral resolution. DESIGN: A double-blind crossover design was used to measure the effect of the noise reduction algorithm ClearVoice on noise tolerance with the acceptable noise level (ANL) test and on speech in noise for three performance levels: speech reception thresholds (SRT) at 50%, 70%, and at a speech to noise ratio of SRT50% + 11 dB. Furthermore, they tested speech intelligibility in quiet. The effective spectral resolution was measured with a spectral-ripple discrimination test. Twenty users of the Advanced Bionics Harmony processor with HiRes120-processing participated in this study. RESULTS: The noise reduction algorithm led to a significant improvement-a decrease of 3.6 dB-in the ANL test but had no significant effect on any of the three speech-in-noise performance levels. The improvement in ANL was not significantly correlated with any of the speech-in-noise measures, nor with the speech-in-noise ratio in the ANL test. However, higher maximum speech intelligibility in quiet conditions correlated significantly with higher noise tolerance. Spectral-ripple discrimination thresholds were not significantly correlated with the effect of noise reduction on ANL or on speech intelligibility in noise nor with the speech-in-noise ratios. The spectral-ripple discrimination thresholds did correlate significantly with maximum speech intelligibility in quiet but not with speech reception thresholds in noise. CONCLUSIONS: The noise reduction algorithm ClearVoice improves noise tolerance. However, this study shows no change in speech intelligibility in noise due to the algorithm. The improvement in noise tolerance is not significantly related to spectral-ripple discrimination thresholds, speech intelligibility measures, or signal to noise ratio. Our hypothesis that CI recipients with low spectral resolution have a greater benefit from noise reduction than CI users with high spectral resolution does not hold for noise tolerance or for speech intelligibility in noise.

The Important Role of Contextual Information in Speech Perception in Cochlear Implant Users and Its Consequences in Speech Tests.

This study investigated the role of contextual information in speech intelligibility, the influence of verbal working memory on the use of contextual information, and the suitability of an ecologically valid sentence test containing contextual information, compared with a CNC (Consonant-Nucleus-Consonant) word test, in cochlear implant (CI) users. Speech intelligibility performance was assessed in 50 postlingual adult CI users on sentence lists and on CNC word lists. Results were compared with a normal-hearing (NH) group. The influence of contextual information was calculated from three different context models. Working memory capacity was measured with a Reading Span Test. CI recipients made significantly more use of contextual information in recognition of CNC words and sentences than NH listeners. Their use of contextual information in sentences was related to verbal working memory capacity but not to age, indicating that the ability to use context is dependent on cognitive abilities, regardless of age. The presence of context in sentences enhanced the sensitivity to differences in sensory bottom-up information but also increased the risk of a ceiling effect. A sentence test appeared to be suitable in CI users if word scoring is used and noise is added for the best performers.

Comparing the Effect of Different Hearing Aid Fitting Methods in Bimodal Cochlear Implant Users.

Purpose The aim of the study was to investigate the effect of 3 hearing aid fitting procedures on provided gain of the hearing aid in bimodal cochlear implant users and their effect on bimodal benefit. Method This prospective study measured hearing aid gain and auditory performance in a cross-over design in which 3 hearing aid fitting methods were compared. Hearing aid fitting methods differed in initial gain prescription rule (NAL-NL2 and Audiogram+) and loudness balancing method (broadband vs. narrowband loudness balancing). Auditory functioning was evaluated by a speech-in-quiet test, a speech-in-noise test, and a sound localization test. Fourteen postlingually deafened adult bimodal cochlear implant users participated in the study. Results No differences in provided gain and in bimodal performance were found for the different hearing aid fittings. For all hearing aid fittings, a bimodal benefit was found for speech in noise and sound localization. Conclusion Our results confirm that cochlear implant users with residual hearing in the contralateral ear substantially benefit from bimodal stimulation. However, on average, no differences were found between different types of fitting methods, varying in prescription rule and loudness balancing method.

Prevalence of age-related hearing loss, including sex differences, in older adults in a large cohort study.

OBJECTIVES/HYPOTHESIS: To obtain actual status of age-related hearing loss in a general unscreened population of older Dutch adults and to investigate whether the prevalence or degree has changed over time. STUDY DESIGN: To investigate the prevalence and degree of hearing loss, we conducted a large prospective cohort study of older adults between February 2011 and July 2015. METHODS: Pure-tone air- and bone-conduction thresholds were measured for 4,743 participants. Results were compared to previous cohort studies. RESULTS: As expected, hearing loss increased with age. We found a correlation of R2 = 0.317 for men and R2 = 0.354 for women (right ears). A prevalence of hearing loss greater than 35 dB hearing level the average of 0.5/1/2/4 kHz in the better ear, was found in 33% of the male and almost 29% of the female participants aged 65 years and older. Compared with previous studies, men had less hearing loss at the frequencies of 2 kHz and above. Hearing thresholds in women were significantly higher at 4 and 8 kHz. The difference in hearing loss between men and women is significantly less than in earlier studies. CONCLUSIONS: Our study confirms that hearing loss is highly prevalent in the general unscreened population of older adults. However, the difference in hearing between sexes was considerably less than previously reported. This is probably due to changing lifestyle and environmental circumstances, LEVEL OF EVIDENCE: 2b Laryngoscope, 127:725-730, 2017.

Psychophysical assessment of spatial spread of excitation in electrical hearing with single and dual electrode contact maskers.

OBJECTIVE: To evaluate psychophysically the spatial spread of excitation in electrical hearing with a new dual contact masker and to investigate under which conditions it is possible to stimulate fibers in the immediate neighborhood of an electrode contact, which were not excited by neighboring electrode contacts. DESIGN: In this study a psychophysical forward masking paradigm with a dual contact masker was used to avoid off-site listening, the electrical analogue of off-frequency listening. The masker stimulus (300 msec) is presented nonsimultaneously on two electrode contacts, one on the apical side and another on the basal side of the probe contact, followed by a probe stimulus of 20 msec.Unmasked probe thresholds were compared with masked ones at a number of masker-probe distances, whereas growth of masking curves were measured for a fixed masker contact pair. Standard selectivity measurements (single contact masking) and the recovery of forward masking with one masker contact were included for comparison with existing methods. All experiments were carried out with six participants who use the Clarion CII device with a HiFocus I electrode array. RESULTS: For dual contact masking the amount of masking was significantly greater than for single contact masking and the width of the masking patterns was on average 1.1 mm broader than for single contact masking, resulting in a broad region of excitation, with masker-probe overlap for distances greater than 3 mm. Masking widths for dual and single contact masking were highly correlated. Growth of masking curves were highly nonlinear. They showed a strong elevation of the slope that starts for most subjects around the middle of the dynamic range or above. For 4 out of 6 subjects, no probe threshold was found above a masker amplitude of about 400-500 microA. The ratio of the maximum measurable masked probe thresholds and unmasked probe threshold ranged from 1.7 to 2.6 (S4 excluded). Recovery of masking functions follow an exponential decay. Time constants tau for the recovery process ranged from 21.6 msec to 114.9 msec. CONCLUSIONS: With a dual contact masker (1) off-site listening can be avoided, leading to larger estimates of the width of excitation patterns than in single contact masking, (2) it can be estimated for which stimulation level there is complete overlap of excitation patterns of adjacent electrode contacts, (3) it can be shown that stimulation of nerve fibers in the immediate neighborhood of an electrode contact which were not excited by neighboring electrode contacts is only possible if the probe stimulation amplitude is sufficiently high in comparison with amplitudes on neighboring contacts.