Using a cochlear implant processor as contralateral routing of signals device in unilateral cochlear implant recipients.

PURPOSE: In unilateral cochlear implant (CI) recipients, a contralateral routing of signals (CROS) device enables to receive auditory information from the unaided side. This study investigates the feasibility as well as subjective and objective benefits of using a CI processor as a CROS device in unilateral CI recipients. METHODS: This is a single-center, prospective cohort study. First, we tested the directionality of the CROS processor in an acoustic chamber. Second, we examined the difference of speech perception in quiet and in noise in ten unilateral CI recipients with and without the CROS processor. Third, subjective ratings with the CROS processor were evaluated according to the Client Oriented Scale of Improvement Questionnaire. RESULTS: There was a time delay between the two devices of 3 ms. Connection of the CROS processor led to a summation effect of 3 dB as well as a more constant amplification along all azimuths. Speech perception in quiet showed an increased word recognition score at 50 dB (mean improvement 7%). In noise, the head shadow effect could be mitigated with significant gain in speech perception (mean improvement 8.4 dB). This advantage was reversed in unfavorable listening situations, where the CROS device considerably amplified the noise (mean: - 4.8 dB). Subjectively, patients who did not normally wear a hearing aid on the non-CI side were satisfied with the CROS device. CONCLUSIONS: The connection and synchronization of a CI processor as a CROS device is technically feasible and the signal processing strategies of the device can be exploited. In contra-laterally unaided patients, a subjective benefit can be achieved when wearing the CROS processor.

Binaural squelch effect in unilateral otosclerosis surgery: comparison of speech intelligibility in noise before-after surgery.

PURPOSE: We aimed to evaluate the speech intelligibility benefit in noise provided by stapedotomy in the treatment of unilateral otosclerosis. METHODS: We enrolled adults suffering from unilateral conductive hearing loss and followed them up until 9 months after surgery. The patients underwent a free field speech hearing evaluation using the French Matrix test before and after stapedotomy. Speech material was sent to the front of the patients (S0) and noise was presented either at the front (N0), or at the operated ear (N-90) or at the non-operated ear (N + 90). The speech intelligibility benefit in noise was assessed by comparing Squelch effect (SE), Head shadow effect (HS) and Binaural redundancy (BR) before and after surgery. SE was measured as the difference in speech reception thresholds (SRT) between S0N + 90 situations before and after surgery, HS as the difference in SRT between S0N + 90 and S0N-90 situations, and BR as the difference in SRT between S0N0 situations before and after surgery. In addition, two quality of life's questionnaires were completed by patients to evaluate their discomfort. RESULTS: Among 25 patients, 19 were followed up during 9 months, 4 were excluded and 2 were lost for the following-up. Stapedotomy provided a restoration of SE of 3.7 dB SNR (p < 0.001) and a BR gain of 1.8 dB SNR (p < 0.001). HS did not show any statistical variation after surgery (p = 0.077). Finally, the questionnaires showed a residual hearing discomfort. CONCLUSION: Stapedotomy provided a binaural benefit with the restoration of the SE and BR but which remained lower than in the normal-hearing population. TRIAL REGISTRATION: The 07/02/2018 on Clinical.Trial.Gouv: NCT03587792.

Can the use of the CROS system provide head shadow effect contribution to unilateral Cochlear Implant Users? / O Sistema CROS pode oferecer contribuição do efeito sombra da cabeça a usuários de implante coclear unilateral?

ABSTRACT Purpose The aim of this study was to evaluate the contribution of the CROS system on the head shadow effect in unilateral implant users. Methods Prospective cross-sectional study, approved by the ethics committee under protocol 2.128.869. Eleven adults with post-lingual deafness users of unilateral Advanced Bionics CI were selected. Speech recognition was evaluated with recorded words presented at 65dBA at 0o azimuth and at 90o on the side contralateral to the CI, with noise at 55dBA, using CI alone and CI + CROS system. The results were analyzed using paired t-test with a 0.05 alpha. Results The mean speech recognition scores were significantly better with CI + CROS in relation to the condition of CI alone (p <0.05, p <0.005 and p <0.005 respectively). In the presentation at 0o azimuth, no significant differences were found. Conclusion Users of unilateral CI without useful residual hearing for the use of hearing aids or unable to undergo bilateral surgery can benefit from the CROS device for speech recognition, especially when the speech is presented on the side contralateral to the CI.

RESUMO Objetivo O objetivo deste estudo foi avaliar o efeito do sistema CROS em fenômenos como efeito sombra da cabeça em usuários de implante coclear unilateral. Método Estudo transversal prospectivo, aprovado pelo conselho de ética sob protocolo 2.128.869. Onze adultos com surdez de instalação pós-lingual usuários de IC Advanced Bionics unilateral foram selecionados. O reconhecimento de fala foi avaliado com palavras gravadas apresentadas a 65dBA a 0o azimute e a (90o no lado contralateral ao IC), com ruído a 55dBA, usando somente o IC e IC+sistema CROS. Os resultados foram analisados usando teste t pareado com alfa de 0,05. Resultados Os escores médios de reconhecimento de fala foram significativamente melhores com IC + CROS em relação à condição apenas IC (p <0,05, p <0,005 e p <0,005 respectivamente). Na apresentação à frente não foram encontradas diferenças significantes. Conclusão Os usuários de IC unilateral sem resíduo útil para uso de prótese auditiva ou impossibilitados de submeter-se à cirurgia bilateral podem se beneficiar do dispositivo CROS para o reconhecimento de fala, sobretudo quando a fala for apresentada ao lado contralateral ao IC.

The Role of Interaural Differences, Head Shadow, and Binaural Redundancy in Binaural Intelligibility Benefits Among School-Aged Children.

In complex listening environments, children can benefit from auditory spatial cues to understand speech in noise. When a spatial separation is introduced between the target and masker and/or listening with two ears versus one ear, children can gain intelligibility benefits with access to one or more auditory cues for unmasking: monaural head shadow, binaural redundancy, and interaural differences. This study systematically quantified the contribution of individual auditory cues in providing binaural speech intelligibility benefits for children with normal hearing between 6 and 15 years old. In virtual auditory space, target speech was presented from + 90° azimuth (i.e., listener's right), and two-talker babble maskers were either co-located (+ 90° azimuth) or separated by 180° (-90° azimuth, listener's left). Testing was conducted over headphones in monaural (i.e., right ear) or binaural (i.e., both ears) conditions. Results showed continuous improvement of speech reception threshold (SRT) between 6 and 15 years old and immature performance at 15 years of age for both SRTs and intelligibility benefits from more than one auditory cue. With early maturation of head shadow, the prolonged maturation of unmasking was likely driven by children's poorer ability to gain full benefits from interaural difference cues. In addition, children demonstrated a trade-off between the benefits from head shadow versus interaural differences, suggesting an important aspect of individual differences in accessing auditory cues for binaural intelligibility benefits during development.

Effects of spatial separation with better- ear listening on N1-P2 complex.

OBJECTIVE: The purpose of this study was to determine better- ear listening effect on spatial separation with the N1-P2 complex. METHODS: Twenty individuals with normal hearing participated in this study. The speech stimulus /ba/ was presented in front of the participant (0°). Continuous Speech Noise (5 dB signal-to-noise ratio) was presented either in front of the participant (0°), left-side (-90°), or right-side (+90°). N1- P2 complex has been recorded in quiet and three noisy conditions. RESULTS: There was a remarkable effect of noise direction on N1, P2 latencies. When the noise was separated from the stimulus, N1 and P2 latency increased in terms of when noise was co-located with the stimulus. There was no statistically significant difference in N1-P2 amplitudes between the stimulus-only and co-located condition. N1-P2 amplitude was increased when the noise came from the sides, according to the stimulus-only and co-located conditions. CONCLUSION: These findings demonstrate that the latency shifts on N1-P2 complex explain cortical mechanisms of spatial separation in better-ear listening.

Application of Wireless Contralateral Routing of Signal (CROS) Technology in Unilateral Cochlear Implant Users. / Aplicación de la tecnología de enrutamiento inalámbrico contralateral de la señal (CROS) en usuarios de implante coclear unilateral.

INTRODUCTION: Single cochlear implantation usually provides substantial speech intelligibility benefits but bilaterally deaf, unilaterally implanted subjects will continue to experience limitations due to the head shadow effect, like single-sided deaf individuals. In the treatment of individuals with single-sided deafness one option is contralateral routing of signal (CROS) devices, which constitute a non-surgical intervention of the second ear in unilaterally implanted individuals. METHOD: Twelve experienced adult cochlear implant users with Naída Q70 processor and the CROS device used in combination participated in the study. For the study 3 conditions were provided: cochlear implant only, omnidirectional microphone mode (CROS deactivated); cochlear implant plus CROS activated, omnidirectional microphone mode and cochlear implant plus CROS activated, UltraZoom mode. Speech reception thresholds were determined in quiet and noise. Subjective feedback regarding the practical usability of the CROS device and the perceived benefit were collected. RESULTS: There was a 27.6% improvement in speech understanding in quiet and 32.5% improvement in noise when CROS device was activated. Using advanced directional microphones, a statistically significant benefit of 35% was obtained. The responses to the questionnaires revealed that the subjects perceived benefit in their everyday lives when using the CROS device with their cochlear implants. CONCLUSION: The investigated CROS device used by unilateral CI recipients in cases where bilateral implantation is not an option provides both subjective and objective speech recognition benefit when the signal is directed to the CROS device. Unfavourable conditions where speech is presented from the cochlear implant side and noise from the CROS side or diffusely were not included in this evaluation since the CROS device adds additional noise and performance is expected to decrease as has previously been shown.

Binaural hearing advantages for children with bimodal fitting.

OBJECTIVES: Bimodal fitting (BF) allows children with cochlear implant to benefit from binaural hearing advantages. Three major binaural hearing advantages, which enhance hearing function of people with normal hearing, are head shadow effect (HSE), binaural squelch effect (BSQ) and binaural summation effect (BSU). This study in pediatric patients attempting to measure the auditory benefits of bimodal stimulation in children with long-standing use of a cochlear implant (CI), and residual hearing on the contralateral side. METHODS: This cross-sectional study investigated binaural advantages in 24 children of 8-12 years who had undergone cochlear implantation in a cochlear implant center in Tehran and continuously used BF. Improved score of speech perception in noise (SPiN) under BF condition, as compared to the application of cochlear implant alone, was a binaural advantage found in this study. Each binaural advantage was measured by obtaining the SPiN score under different listening and noise conditions, using relevant formulas. The measured value of each advantage reflects the improved score of SPiN, caused by that certain advantage. RESULTS: In this study, improved mean SPiN score caused by the HSE, BSQ and BSU was, respectively, 3.13, 1.42 and 2.04 dB, indicating greater binaural advantages and hence improved SPiN, under BF condition in comparison with cochlear implant alone. CONCLUSION: Children with unilateral cochlear implant and measurable residual hearing in non-implanted ear can benefit from binaural advantages and better SPiN when hearing aid is used in the unaided ear.

Head shadow enhancement with low-frequency beamforming improves sound localization and speech perception for simulated bimodal listeners.

Many hearing-impaired listeners struggle to localize sounds due to poor availability of binaural cues. Listeners with a cochlear implant and a contralateral hearing aid - so-called bimodal listeners - are amongst the worst performers, as both interaural time and level differences are poorly transmitted. We present a new method to enhance head shadow in the low frequencies. Head shadow enhancement is achieved with a fixed beamformer with contralateral attenuation in each ear. The method results in interaural level differences which vary monotonically with angle. It also improves low-frequency signal-to-noise ratios in conditions with spatially separated speech and noise. We validated the method in two experiments with acoustic simulations of bimodal listening. In the localization experiment, performance improved from 50.5∘ to 26.8∘ root-mean-square error compared with standard omni-directional microphones. In the speech-in-noise experiment, speech was presented from the frontal direction. Speech reception thresholds improved by 15.7 dB SNR when the noise was presented from the cochlear implant side, improved by 7.6 dB SNR when the noise was presented from the hearing aid side, and was not affected when noise was presented from all directions. Apart from bimodal listeners, the method might also be promising for bilateral cochlear implant or hearing aid users. Its low computational complexity makes the method suitable for application in current clinical devices.

Effect of spatial separation and noise type on sentence recognition by Mandarin-speaking cochlear implant users.

OBJECTIVES: To investigate the effects of spatial separation and noise type on sentence recognition by unilateral Mandarin-speaking cochlear implant (CI) users and normal-hearing (NH) listeners. METHOD: Twenty-two unilateral Mandarin-speaking CI users and six NH listeners participated in this study. Speech reception thresholds were measured for three noise types (steady state noise, speech babble, and music). Sentences from the Mandarin Speech Perception test were presented directly in front of the listener (0°). Noise was presented from one of the five speaker locations: -90°, -45°, 0°, +45°, and +90°. RESULTS: Overall, CI performance was significantly poorer than NH performance for all spatial separation and noise type conditions. NH listeners performed best with music and poorest with steady noise. CI users performed best with steady noise, and poorest with babble. Performance was significantly affected by noise location and noise type. There was no significant difference in head shadow effects among the different noise types for CI users. CONCLUSIONS: Performance was much poorer in CI than in NH listeners for all noise types and spatial separations. Noise type differently affected unilateral CI users and NH listeners. The limited spectral resolution in CI users did not appear to affect head shadow.

Binaural squelch and head shadow effects in children with unilateral cochlear implants and contralateral hearing aids.

The aim of this study was to investigate the amount of binaural squelch effect (BSE) and head shadow effect (HSE) in children who use unilateral cochlear implants (CI) and contralateral hearing aids (HA). The study group consisted of 19 CI recipient children who consistently wore a contralateral HA. Speech sounds were used to evaluate speech perception performance in noise. Testing was performed in three listening conditions: (1) bimodal listening with noise source on HA side; (2) CI only with noise source contralaterally (HA off); (3) CI only with noise source on the CI side. Statistical analysis revealed a significant difference between the three listening conditions and post hoc tests indicated significant differences for all pairwise comparisons (p < 0.001). The average BSE and HSE were 11.8% and 17.1% respectively. The majority of bimodal CI users showed BSE and HSE with significant speech perception improvement in the presence of noise.

Single-sided deafness and directional hearing: contribution of spectral cues and high-frequency hearing loss in the hearing ear.

Direction-specific interactions of sound waves with the head, torso, and pinna provide unique spectral-shape cues that are used for the localization of sounds in the vertical plane, whereas horizontal sound localization is based primarily on the processing of binaural acoustic differences in arrival time (interaural time differences, or ITDs) and sound level (interaural level differences, or ILDs). Because the binaural sound-localization cues are absent in listeners with total single-sided deafness (SSD), their ability to localize sound is heavily impaired. However, some studies have reported that SSD listeners are able, to some extent, to localize sound sources in azimuth, although the underlying mechanisms used for localization are unclear. To investigate whether SSD listeners rely on monaural pinna-induced spectral-shape cues of their hearing ear for directional hearing, we investigated localization performance for low-pass filtered (LP, <1.5 kHz), high-pass filtered (HP, >3kHz), and broadband (BB, 0.5-20 kHz) noises in the two-dimensional frontal hemifield. We tested whether localization performance of SSD listeners further deteriorated when the pinna cavities of their hearing ear were filled with a mold that disrupted their spectral-shape cues. To remove the potential use of perceived sound level as an invalid azimuth cue, we randomly varied stimulus presentation levels over a broad range (45-65 dB SPL). Several listeners with SSD could localize HP and BB sound sources in the horizontal plane, but inter-subject variability was considerable. Localization performance of these listeners strongly reduced after diminishing of their spectral pinna-cues. We further show that inter-subject variability of SSD can be explained to a large extent by the severity of high-frequency hearing loss in their hearing ear.

Bilateral cochlear implantation for children in nagasaki, Japan.

OBJECTIVES: The number of patients with bilateral cochlear implant (CI) has gradually increased as patients and/or parents recognize its effectiveness. The purpose of this report is to evaluate the efficacy of 29 bilateral CI out of 169 pediatric CI users, who received auditory-verbal/oral habilitation at our hearing center. METHODS: We evaluated the audiological abilities 29 Japanese children with bilateral CIs including wearing threshold, word recognition score, speech discrimination score at 1 m from front speaker (SP), 1 m from second CI side SP, speech discrimination score under the noise (S/N ratio=80 dB sound pressure level [SPL]/70 dB SPL, 10 dB) at 1 m from front SP, word recognition score under the noise (S/N ratio=80 dB SPL/70 dB SPL, 10 dB) at 1 m from front SP. RESULTS: Binaural hearing using bilateral CI is better than first CI in all speech understanding tests. Especially, there were significant differences between the results of first CI and bilateral CI on SDS at 70 dB SPL (P=0.02), SDS at 1 m from second CI side SP at 60 dB SPL (P=0.02), word recognition score (WRS) at 1 m from second CI side SP at 60 dB SPL (P=0.02), speech discrimination score (SDS) at 1 m from front SP under the noise (S/N=80/70; P=0.01) and WRS at 1 m from front SP under the noise (S/N=80/70; P=0.002). At every age, a second CI is very effective. However, the results of under 9 years old were better than of over 9 years old on the mean SDS under the noise (S/N=80/70) on second CI (P=0.04). About use of a hearing aid (HA) in their opposite side of first CI, on the WRS and SDS under the noise, there were significant differences between the group of over 3 years and the group of under 10 months of HA non user before second CI. CONCLUSION: These results may show important binaural effectiveness such as binaural summation and head shadow effect. Bilateral CI is very useful medical intervention for many children with severe-to-profound hearing loss in Japan as well as elsewhere.

Bilateral Cochlear Implantation for Children in Nagasaki, Japan

OBJECTIVES: The number of patients with bilateral cochlear implant (CI) has gradually increased as patients and/or parents recognize its effectiveness. The purpose of this report is to evaluate the efficacy of 29 bilateral CI out of 169 pediatric CI users, who received auditory-verbal/oral habilitation at our hearing center. METHODS: We evaluated the audiological abilities 29 Japanese children with bilateral CIs including wearing threshold, word recognition score, speech discrimination score at 1 m from front speaker (SP), 1 m from second CI side SP, speech discrimination score under the noise (S/N ratio=80 dB sound pressure level [SPL]/70 dB SPL, 10 dB) at 1 m from front SP, word recognition score under the noise (S/N ratio=80 dB SPL/70 dB SPL, 10 dB) at 1 m from front SP. RESULTS: Binaural hearing using bilateral CI is better than first CI in all speech understanding tests. Especially, there were significant differences between the results of first CI and bilateral CI on SDS at 70 dB SPL (P=0.02), SDS at 1 m from second CI side SP at 60 dB SPL (P=0.02), word recognition score (WRS) at 1 m from second CI side SP at 60 dB SPL (P=0.02), speech discrimination score (SDS) at 1 m from front SP under the noise (S/N=80/70; P=0.01) and WRS at 1 m from front SP under the noise (S/N=80/70; P=0.002). At every age, a second CI is very effective. However, the results of under 9 years old were better than of over 9 years old on the mean SDS under the noise (S/N=80/70) on second CI (P=0.04). About use of a hearing aid (HA) in their opposite side of first CI, on the WRS and SDS under the noise, there were significant differences between the group of over 3 years and the group of under 10 months of HA non user before second CI. CONCLUSION: These results may show important binaural effectiveness such as binaural summation and head shadow effect. Bilateral CI is very useful medical intervention for many children with severe-to-profound hearing loss in Japan as well as elsewhere.