Noise reduction technologies implemented in head-worn preprocessors for improving cochlear implant performance in reverberant noise fields

The purpose of this study was to investigate whether a multichannel adaptive directional microphone and a modulation-based noise reduction algorithm could enhance cochlear implant performance in reverberant noise fields. A hearing aid was modified to output electrical signals (ePreprocessor) and a cochlear implant speech processor was modified to receive electrical signals (eProcessor). The ePreprocessor was programmed to flat frequency response and linear amplification. Cochlear implant listeners wore the ePreprocessor-eProcessor system in three reverberant noise fields: 1) one noise source with variable locations; 2) three noise sources with variable locations; and 3) eight evenly spaced noise sources from 0° to 360°. Listeners' speech recognition scores were tested when the ePreprocessor was programmed to omnidirectional microphone (OMNI), omnidirectional microphone plus noise reduction algorithm (OMNI?+?NR), and adaptive directional microphone plus noise reduction algorithm (ADM?+?NR). They were also tested with their own cochlear implant speech processor (CI_OMNI) in the three noise fields. Additionally, listeners rated overall sound quality preferences on recordings made in the noise fields. Results indicated that ADM+NR produced the highest speech recognition scores and the most preferable rating in all noise fields. Factors requiring attention in the hearing aid-cochlear implant integration process are discussed.     

Sequential bilateral cochlear implantation in a patient with bilateral Ménière's disease

This case study describes a 45-yr-old female with bilateral, profound sensorineural hearing loss due to Ménière's disease. She received her first cochlear implant in the right ear in 2008 and the second cochlear implant in the left ear in 2010. The case study examines the enhancement to speech recognition, particularly in noise, provided by bilateral cochlear implants. Speech recognition tests were administered prior to obtaining the second implant and at a number of test intervals following activation of the second device. Speech recognition in quiet and noise as well as localization abilities were assessed in several conditions to determine bilateral benefit and performance differences between ears. The results of the speech recognition testing indicated a substantial improvement in the patient's ability to understand speech in noise and her ability to localize sound when using bilateral cochlear implants compared to using a unilateral implant or an implant and a hearing aid. In addition, the patient reported considerable improvement in her ability to communicate in daily life when using bilateral implants versus a unilateral implant. This case suggests that cochlear implantation is a viable option for patients who have lost their hearing to Ménière's disease even when a number of medical treatments and surgical interventions have been performed to control vertigo. In the case presented, bilateral cochlear implantation was necessary for this patient to communicate successfully at home and at work.     

A directional remote-microphone for bimodal cochlear implant recipients

Abstract

To evaluate whether speech recognition in noise differs according to whether a wireless remote microphone is connected to just the cochlear implant (CI) or to both the CI and to the hearing aid (HA) in bimodal CI users. The second aim was to evaluate the additional benefit of the directional microphone mode compared with the omnidirectional microphone mode of the wireless microphone. This prospective study measured Speech Recognition Thresholds (SRT) in babble noise in a ‘within-subjects repeated measures design’ for different listening conditions. Eighteen postlingually deafened adult bimodal CI users. No difference in speech recognition in noise in the bimodal listening condition was found between the wireless microphone connected to the CI only and to both the CI and the HA. An improvement of 4.1?dB was found for switching from the omnidirectional microphone mode to the directional mode in the CI only condition. The use of a wireless microphone improved speech recognition in noise for bimodal CI users. The use of the directional microphone mode led to a substantial additional improvement of speech perception in noise for situations with one target signal.     

Should a hearing aid in the contralateral ear be recommended for children with a unilateral cochlear implant?

OBJECTIVES: To predict bimodal benefit before cochlear implantation, we compared the performances of participants with bimodal fitting and with a cochlear implant alone on speech perception tests. METHODS: Twenty-two children with a cochlear implant in one ear and a hearing aid in the other (bimodal fitting) were included. Several aided and unaided average hearing thresholds and the aided word recognition score of the hearing aid ear were related to the bimodal benefit on a phoneme recognition test in quiet and in noise. Results with bimodal fitting were compared to results with the cochlear implant alone on a phoneme recognition test in quiet and in noise. RESULTS: No relationship was found between any of the hearing thresholds or the aided phoneme recognition score of the hearing aid ear and the bimodal benefit on the phoneme recognition tests. At the group level, the bimodal scores on the phoneme recognition tests in quiet and in noise were significantly better than the scores with the cochlear implant alone. CONCLUSIONS: Preoperatively available audiometric parameters are not reliable predictors of bimodal benefit in candidates for cochlear implantation. Children with unilateral implants benefit from bimodal fitting on speech tests. This improvement in performance warrants the recommendation of bimodal fitting even when bimodal benefit cannot be predicted.     

Single channel cochlear implant: application to three patients

Single channel cochlear implant of 3M/House design was implanted to the three patients with profound hearing loss. Before the implantation, use of hearing aid had not afforded serviceable hearing enough for speech recognition in these patients. Postoperative courses were uneventful. Speech rehabilitation was started at 3 weeks after the surgery. The speech tracking scores with the cochlear implant plus lipreading achieved 20-25 bunsetues (the minimum meaningful unit of the Japanese sentence) per minute at three or four months after the operation. All the patients could recognize speech of daily life with help of lipreading. However, speech recognition by the cochlear implant alone was not satisfactory.     

Patients utilizing a hearing aid and a cochlear implant: speech perception and localization

OBJECTIVE: The purpose of this pilot study was to document speech perception and localization abilities in patients who use a cochlear implant in one ear and a hearing aid in the other ear. DESIGN: We surveyed a group of 111 cochlear implant patients and asked them whether they used a hearing aid on their unimplanted ear. The first three patients who were available were tested on word and sentence recognition and localization tasks. Speech stimuli were presented from the front in quiet and in noise. In the latter conditions, noise was either from the front, the right, or the left. Localization was tested with noise bursts presented at 45 degrees from the right or left. In addition we asked the patients about their abilities to integrate the information from both devices. RESULTS: Speech perception tests in quiet showed a binaural advantage for only one of the three patients for words and none for sentences. With speech and noise both in front of the patient, two patients performed better with both devices than with either device alone. With speech in front and noise on the hearing aid side, no binaural advantage was seen, but with noise on the cochlear implant side, one patient showed a binaural advantage. Localization ability improved with both devices for two patients. The third patient had above-chance localization ability with his implant alone. CONCLUSIONS: A cochlear implant in one ear and a hearing aid in the other ear can provide binaural advantages. The patient who did not show a clear binaural advantage had the poorest hearing aid alone performance. The absolute and relative levels of performance at each ear are likely to influence the potential for binaural integration.     

A longitudinal study of the bilateral benefit in children with bilateral cochlear implants

Objective: To study the development of the bilateral benefit in children using bilateral cochlear implants by measurements of speech recognition and sound localization. Design: Bilateral and unilateral speech recognition in quiet, in multi-source noise, and horizontal sound localization was measured at three occasions during a two-year period, without controlling for age or implant experience. Longitudinal and cross-sectional analyses were performed. Results were compared to cross-sectional data from children with normal hearing. Study sample: Seventy-eight children aged 5.1–11.9 years, with a mean bilateral cochlear implant experience of 3.3 years and a mean age of 7.8 years, at inclusion in the study. Thirty children with normal hearing aged 4.8–9.0 years provided normative data. Results: For children with cochlear implants, bilateral and unilateral speech recognition in quiet was comparable whereas a bilateral benefit for speech recognition in noise and sound localization was found at all three test occasions. Absolute performance was lower than in children with normal hearing. Early bilateral implantation facilitated sound localization. Conclusions: A bilateral benefit for speech recognition in noise and sound localization continues to exist over time for children with bilateral cochlear implants, but no relative improvement is found after three years of bilateral cochlear implant experience.     

1-year postactivation results for sequentially implanted bilateral cochlear implant users.

OBJECTIVE: Evaluate speech recognition in quiet and in noise for a group of 12 children, all of whom underwent sequential bilateral cochlear implantation at various ages (range, 1 yr, 8 mo to 9 yr, 6 mo at time of second implant). STUDY DESIGN: Retrospective. SETTING: Outpatient cochlear implant clinic. PATIENTS: Children who underwent sequential bilateral cochlear implantation. INTERVENTION: Rehabilitative. MAIN OUTCOME MEASURES: Speech recognition in quiet was evaluated for each ear separately using single-word speech recognition assessments (Multisyllabic Lexical Neighborhood Test and Early Speech Perception Test) via recorded presentation. Speech recognition in noise was assessed for each ear separately and in the bilateral condition by obtaining a spondee recognition threshold in the presence of speech-weighted noise presented at 45 dB hearing level. The primary outcome measure for speech recognition in noise assessment was the signal-to-noise ratio for 50% performance, which was calculated by determining the difference between the presentation level of the noise and the presentation level at which the speech recognition threshold was obtained. The results of these assessments were contrasted between children receiving their second cochlear implant before 4 years of age and children receiving their second cochlear implant after 4 years of age. RESULTS: A statistically significant difference for speech recognition scores in quiet was obtained between the early-implanted ear and the late-implanted ears for children receiving their second cochlear implant after 4 years of age. There was not a statistically significant difference in speech recognition scores in quiet between the early-implanted and late-implanted ears of children receiving their second cochlear before 4 years of age. Both groups of children possessed better speech recognition scores in noise (statistically significant at an alpha = 0.05) in the bilateral condition relative to either unilateral condition. However, there was not a statistically significant relationship between speech recognition performance in noise and the duration of deafness of the later implanted ear. CONCLUSION: Bilateral cochlear implantation allowed for better speech recognition in noise relative to unilateral performance for a group of 12 children who underwent sequential bilateral cochlear implantation at various ages. There was not a statistically significant relationship between speech recognition in noise benefit, which was defined as the difference in performance between the first implanted ear and the bilateral condition and the age at which the second implant was received. Children receiving bilateral cochlear implants younger than 4 years of age achieved better speech recognition in quiet performance for the later implanted ear as compared with children receiving their second cochlear implant after 4 year of age.     

Quantification of directional benefit across different polar response patterns

The purpose of this study was to assess the relationship between the directivity of a directional microphone hearing aid and listener performance. Hearing aids were fit bilaterally to 19 subjects with sensorineural hearing loss, and five microphone conditions were assessed: omnidirectional, cardioid, hypercardioid, supercardioid, and "monofit," wherein the left hearing aid was set to omnidirectional and the right hearing aid to hypercardioid. Speech perception performance was assessed using the Hearing in Noise Test (HINT) and the Connected Speech Test (CST). Subjects also assessed eight domains of sound quality for three stimuli (speech in quiet, speech in noise, and music). A diffuse soundfield system composed of eight loudspeakers forming the corners of a cube was used to output the background noise for the speech perception tasks and the three stimuli used for sound quality judgments. Results indicated that there were no significant differences in the HINT or CST performance, or sound quality judgments, across the four directional microphone conditions when tested in a diffuse field. Of particular interest was the monofit condition: Performance on speech perception tests was the same whether one or two directional microphones were used.     

Comparison of two frequency-to-electrode maps for acoustic-electric stimulation

The fitting of a cochlear implant together with aided residual hearing was evaluated by means of matching frequency and/or perceived pitch between acoustic and electric modalities. Five cochlear implant users with the Nucleus^® Freedom? electrode array with residual acoustic hearing participated. Psychophysical procedures were used to create a map in which the implant was programmed to provide the listener with high-frequency information only above the frequency at which acoustic hearing was no longer considered useful. This was compared to a second map which provided the full frequency range. Listeners wore each map for a number of weeks before speech recognition was measured in quiet and noise. Post-operatively across subjects, average hearing thresholds worsened by 27 dB. However, cochlear implantation provided superior recognition of speech compared to pre-operative scores, with the best results found when subjects were wearing their hearing aids together with the implant. No significant differences were found between the two maps on speech tests when subjects were wearing their implant together with hearing aid/s. In conclusion, the combination of a cochlear implant together with hearing aid/s was effective at providing speech perception benefits for the listeners of the current study, regardless of the frequency-to-electrode allocation selected.     

Evaluation of an adaptive,directional-microphone hearing aid

The effectiveness of adaptive directional processing for improvement of speech recognition in comparison to non-adaptive directional and omni-directional processing was examined across four listening environments intended to simulate those found in the real world. The test environment was a single, moderately reverberant room with four loudspeaker configurations: three with fixed discrete noise source positions and one with a single panning noise source. Sentence materials from the Hearing in Noise Test (HINT) and Connected Speech Test (CST) were selected as test materials. Speech recognition across all listening conditions was evaluated for 20 listeners fitted binaurally with Phonak Claro behind-the-ear (BTE) style hearing aids. Results indicated improved speech recognition performance with adaptive and non-adaptive directional processing over that measured with the omnidirectional processing across all four listening conditions. While the magnitudes of directional benefit provided to subjects listening in adaptive and fixed directional modes were similar in some listening environments, a significant speech recognition advantage was measured for the adaptive mode in specific conditions. The advantage for adaptive over fixed directional processing was most prominent when a competing noise was presented from the listener's sides (both fixed and panning noise conditions), and was partially predictable from electroacoustically measured directional pattern data.     

Bone-anchored hearing aid system application for unilateral congenital conductive hearing impairment: audiometric results.

OBJECTIVE: To study the audiologic outcome of bone-anchored hearing aid (BAHA) application in patients with congenital unilateral conductive hearing impairment. STUDY DESIGN: Prospective audiometric evaluation on 20 patients. SETTING: Tertiary referral center. PATIENTS: The experimental group comprised 20 consecutive patients with congenital unilateral conductive hearing impairment, with a mean air-bone gap of 50 dB. METHODS: Aided and unaided hearing was assessed using sound localization and speech recognition-in-noise tests. RESULTS: Aided hearing thresholds and aided speech perception thresholds were measured to verify the effect of the BAHA system on the hearing acuity. All patients fulfilled the criteria that the aided speech reception thresholds or the mean aided sound field thresholds were 25 dB or better in the aided situation. Most patients were still using the BAHA almost every day. Sound localization scores varied widely in the unaided and aided situations. Many patients showed unexpectedly good unaided performance. However, nonsignificant improvements of 3.0 (500 Hz) and 6.9 degrees (3,000 Hz) were observed in favor of the BAHA. Speech recognition in noise with spatially separated speech and noise sources also improved after BAHA implantation, but not significantly. CONCLUSION: Some patients with congenital unilateral conductive hearing impairment had such good directional hearing and speech-in-noise scores in the unaided situation that no overall significant improvement occurred after BAHA fitting in our setup. Of the 18 patients with a complete data set, 6 did not show any significant improvement at all. However, compliance with BAHA use in this patient group was remarkably high. Observations of consistent use of the device are highly suggestive of patient benefit. Further research is recommended to get more insight into these findings.     

Sequential bilateral cochlear implant: results in children and adolescents

IntroductionThe use of the bilateral cochlear implants can promote the symmetrical development of the central auditory pathways, thus benefiting the development of auditory abilities and improving sound localization and the ability of auditory speech perception in situations of competitive noise.ObjectiveTo evaluate the ability of speech perception in children and adolescents using sequential bilateral cochlear implants, considering the association of these variables: age at surgery, time of device use and interval between surgeries.MethodsA total of 14 individuals between 10 and 16 years of age, who demonstrated surgical indication for the use of sequential bilateral cochlear implants as intervention in the auditory habilitation process, were assessed. The speech perception ability was assessed through sentence lists constructed in the Portuguese language, presented in two situations: in silence, with fixed intensity of 60 dB SPL, and in competitive noise, with a signal-to-noise ratio of +15 dB. The evaluation was performed under the following conditions: unilateral with the first activated cochlear implant, unilateral with the second activated cochlear implant and bilateral with both devices activated.ResultsThe results of the speech perception tests showed better performance in both silence and in noise for the bilateral cochlear implant condition when compared to the 1st cochlear implant and the 2nd cochlear implant alone. A worse result of speech perception was found using the 2nd cochlear implant alone. No statistically significant correlation was found between age at the surgical procedure, interval between surgeries and the time of use of the 2nd cochlear implant, and the auditory speech perception performance for all assessed conditions. The use of a hearing aid prior to the 2nd cochlear implant resulted in benefits for auditory speech perception with the 2nd cochlear implant, both in silence and in noise.ConclusionThe bilateral cochlear implant provided better speech perception in silence and in noise situations when compared to the unilateral cochlear implant, regardless of the interval between surgeries, age at the surgical procedure and the time of use of the 2nd cochlear implant. Speech perception with the 1st cochlear implant was significantly better than with the 2nd cochlear implant, both in silence and in noise. The use of the hearing aid prior to the 2nd cochlear implant influenced speech perception performance with the 2nd cochlear implant, both in silence and in noise.     

Speech recognition in quiet and noise in borderline cochlear implant candidates

The present study 1) examined speech recognition at three intensity levels and in noise for adults with bilateral hearing loss who wore amplification and were referred for cochlear implant evaluation but did not meet current audiological criteria, and 2) compared their performance to cochlear implant recipients using current implant technology. When tested at 70 dB SPL, hearing aid subjects' word and sentence recognition scores were similar to or greater than the scores of cochlear implant recipients. Compared to their implanted peers, however, subjects' scores were significantly poorer at normal (60 dB SPL) and soft (50 dB SPL) presentation levels for words and at soft levels for sentences; detection thresholds were also significantly poorer at 1000 Hz and above. The assessment of candidates at louder-than-normal levels (i.e., 70 dB SPL) may not correctly portray their day-to-day communication struggles.     

Speech understanding in quiet and noise in bilateral users of the MED-EL COMBI 40/40+ cochlear implant system

OBJECTIVE: The purpose of the study was to investigate speech understanding in quiet and noise in subjects bilaterally implanted with multi-channel cochlear implants. DESIGN: Nine adults bilaterally implanted with MED-EL implants were included in the study. The subjects were tested in three conditions: with both implants, with the right implant only, and with the left implant only. Speech tests included monosyllables in quiet and sentences in noise (10 dB signal to noise ratio). Speech was presented from the front, and noise was presented from either 90 degrees or 270 degrees azimuth. RESULTS: All subjects reported benefit from bilateral stimulation. Speech scores for all subjects were higher with bilateral than with unilateral stimulation. The average score across subjects for sentence understanding was 31.1 percentage points higher with both cochlear implants compared with the cochlear implant ipsilateral to the noise, and 10.7 percentage points higher with both cochlear implants compared with the cochlear implant contralateral to the noise. The average score for recognition of monosyllabic words was 18.7 percentage points higher with both cochlear implants than with one cochlear implant. All of these differences in average scores were significant at the 5% level. CONCLUSIONS: Bilateral cochlear implantation provides a significant benefit in speech understanding in both quiet and noise.     

The effects of changes in head angle on auditory and visual input for omnidirectional and directional microphone hearing aids

Improving the signal-to-noise ratio (SNR) for individuals with hearing loss who are listening to speech in noise provides an obvious benefit. Although binaural hearing provides the greatest advantage over monaural hearing in noise, some individuals with symmetrical hearing loss choose to wear only one hearing aid. The present study tested the hypothesis that individuals with symmetrical hearing loss fit with one hearing aid would demonstrate improved speech recognition in background noise with increases in head turn. Fourteen individuals were fit monaurally with a Starkey Gemini in-the-ear (ITE) hearing aid with directional and omnidirectional microphone modes. Speech recognition performance in noise was tested using the audiovisual version of the Connected Speech Test (CST v.3). The test was administered in auditory-only conditions as well as with the addition of visual cues for each of three head angles: 0 degrees, 20 degrees, and 40 degrees. Results indicated improvement in speech recognition performance with changes in head angle for the auditory-only presentation mode at the 20 degrees and 40 degrees head angles when compared to 0 degrees. Improvement in speech recognition performance for the auditory + visual mode was noted for the 20 degrees head angle when compared to 0 degrees. Additionally, a decrement in speech recognition performance for the auditory + visual mode was noted for the 40 degrees head angle when compared to 0 degrees. These results support a speech recognition advantage for listeners fit with one ITE hearing aid listening in a close listener-to-speaker distance when they turn their head slightly in order to increase signal intensity.     

人工耳蜗植入大龄青年听觉康复个案分析

目的通过1例人工耳蜗植入大龄青年听觉康复实践,探索成年听障患者人工耳蜗植入后听觉训练的方法,旨在为有一定听力语言基础大龄语前聋青年的人工耳蜗术后康复训练提供参考依据。方法采用业余指导的方法和技巧,以患者自主感受、反馈、纠错的康复训练形式为主,定时进行辅导和评估。结果经过4个月听觉康复训练,个案言语识别平均值从术前84．3%高到99．6％;选择性听取平均识别率从术前82％提高到100％。人工耳蜗与助听器同时配戴,听力补偿效果更佳。结论有一定听力语言基础、长期配戴助听器的大龄语前聋青年,在正确认识人工耳蜗期望值的基础上可植入人工耳蜗,经过正确的听力语言康复训练,可以达到听力重建的效果,提高其听辨能力和言语清晰度,增强适应社会环境及交往的能力。     

Speech perception for adults who use hearing aids in conjunction with cochlear implants in opposite ears.

This study aimed to (a) investigate the effect of using a hearing aid in conjunction with a cochlear implant in opposite ears on speech perception in quiet and in noise, (b) identify the speech information obtained from a hearing aid that is additive to the information obtained from a cochlear implant, and (c) explore the relationship between aided thresholds in the nonimplanted ear and speech perception benefit from wearing a hearing aid in conjunction with a cochlear implant in opposite ears.Fourteen adults who used the Nucleus 24 cochlear implant system in 1 ear participated in the study. All participants had either used a hearing aid in the nonimplanted ear for at least 75% of waking hours after cochlear implantation, and/or, hearing loss less than 90 dB HL in the low frequencies in the nonimplanted ear. Speech perception was evaluated in 3 conditions: cochlear implant alone (CI), hearing aid alone (HA), and cochlear implant in conjunction with hearing aid in opposite ears (CIHA). Three speech perception tests were used: consonant-vowel nucleus-consonant (CNC) words in quiet, City University of New York style (CUNY) sentences in coincident signal and noise, and spondees in coincidental and spatially separated signal and noise. Information transmission analyses were performed on the CNC responses.Of the 14 participants tested, 6 showed significant bimodal benefit on open-set speech perception measures and 5 showed benefit on close-set spondees. However, 2 participants showed poorer speech perception with CIHA than CI in at least 1 of the speech perception tests. Results of information transmission analyses showed that bimodal benefit (performance with CIHA minus that with CI) in quiet arises from improved perception of the low frequency components in speech. Results showed that participants with poorer aided thresholds in the mid-to-high frequencies demonstrated greater bimodal benefit. It is possible that the mid-to-high frequency information provided by the hearing aids may be conflicting with the cochlear implants.     

Bimodal studies using adaptive dynamic range optimization (ADRO) technology

This study investigated the effects of adaptive dynamic range optimization (ADRO) processing for six bimodal listeners who used a hearing aid in one ear and a cochlear implant in the other. 'Bimodal' refers to the use of acoustic and electrical stimulation together. Bimodal speech recognition thresholds with the Japanese hearing in noise test were significantly lower for two ADRO devices than two non-ADRO devices in quiet, in noise from the front, and in noise from the implanted side. When the noise was presented from the non-implanted side there was no significant difference between the ADRO and non-ADRO conditions. The hearing aid measure of contrast questionnaire indicated that participants preferred ADRO in 77.3% of situations. ADRO was especially preferred in more difficult situations. The ADRO processing was designed for use in bimodal prostheses, and this study confirmed that speech intelligibility and sound quality improvements are obtainable by using ADRO in a bimodal context.