Advanced Beamformers for Cochlear Implant Users: Acute Measurement of Speech Perception in Challenging Listening Conditions

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Abstract

Objective

To investigate the performance of monaural and binaural beamforming technology with an additional noise reduction algorithm, in cochlear implant recipients.

Method

This experimental study was conducted as a single subject repeated measures design within a large German cochlear implant centre. Twelve experienced users of an Advanced Bionics HiRes90K or CII implant with a Harmony speech processor were enrolled. The cochlear implant processor of each subject was connected to one of two bilaterally placed state-of-the-art hearing aids (Phonak Ambra) providing three alternative directional processing options: an omnidirectional setting, an adaptive monaural beamformer, and a binaural beamformer. A further noise reduction algorithm (ClearVoice) was applied to the signal on the cochlear implant processor itself. The speech signal was presented from 0° and speech shaped noise presented from loudspeakers placed at ±70°, ±135° and 180°. The Oldenburg sentence test was used to determine the signal-to-noise ratio at which subjects scored 50% correct.

Results

Both the adaptive and binaural beamformer were significantly better than the omnidirectional condition (5.3 dB±1.2 dB and 7.1 dB±1.6 dB (p<0.001) respectively). The best score was achieved with the binaural beamformer in combination with the ClearVoice noise reduction algorithm, with a significant improvement in SRT of 7.9 dB±2.4 dB (p<0.001) over the omnidirectional alone condition.

Conclusions

The study showed that the binaural beamformer implemented in the Phonak Ambra hearing aid could be used in conjunction with a Harmony speech processor to produce substantial average improvements in SRT of 7.1 dB. The monaural, adaptive beamformer provided an averaged SRT improvement of 5.3 dB.

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Most cited references 28

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Recognition of speech presented at soft to loud levels by adult cochlear implant recipients of three cochlear implant systems.

P A Wackym, Leigh Peterson, Jameson K. Holden … (2004)

The purpose of this study was to conduct a large-scale investigation with adult recipients of the Clarion, Med-El, and Nucleus cochlear implant systems to (1) determine average scores and ranges of performance for word and sentence stimuli presented at three intensity levels (70, 60, and 50 dB SPL); (2) provide information on the variability of scores for each subject by obtaining test-retest measures for all test conditions; and (3) further evaluate the potential use of lower speech presentation levels (i.e., 60 and/or 50 dB SPL) in cochlear implant candidacy assessment. Seventy-eight adult cochlear implant recipients, 26 with each of the three cochlear implant systems, participated in the study. To ensure that the data collected reflect the range of performance of adult recipients using recent technology for the three implant systems (Clarion HiFocus I or II, Med-El Combi 40+, Nucleus 24M or 24R), a composite range and distribution of consonant-nucleus-consonant (CNC) monosyllabic word scores was determined. Subjects using each device were selected to closely represent this range and distribution of CNC performance. During test sessions, subjects were administered the Hearing in Noise Test (HINT) sentence test and the CNC word test at three presentation levels (70, 60, and 50 dB SPL). HINT sentences also were administered at 60 dB SPL with a signal-to-noise ratio (SNR) of +8 dB. Warble tones were used to determine sound-field threshold levels from 250 to 4000 Hz. Test-retest measures were obtained for each of the speech recognition tests as well as for warble-tone sound-field thresholds. Cochlear implant recipients using the Clarion, Med-El, or Nucleus devices performed on average equally as well at 60 compared with 70 dB SPL when listening for words and sentences. Additionally, subjects had substantial open-set speech perception performance at the softer level of 50 dB SPL for the same stimuli; however, subjects' ability to understand speech was poorer when listening in noise to signals of greater intensity (60 dB SPL + 8 SNR) than when listening to signals presented at a soft presentation level (50 dB SPL) in quiet. A significant correlation was found between sound-field thresholds and speech recognition scores for presentation levels below 70 dB SPL. The results demonstrated a high test-retest reliability with cochlear implant users for these presentation levels and stimuli. Average sound-field thresholds were between 24 and 29 dB HL for frequencies of 250 to 4000 Hz, and results across sessions were essentially the same. Speech perception measures used with cochlear implant candidates and recipients should reflect the listening challenges that individuals encounter in natural communication situations. These data provide the basis for recommending new candidacy criteria based on speech recognition tests presented at 60 and/or 50 dB SPL, intensity levels that reflect real-life listening, rather than 70 dB SPL.

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Simultaneous bilateral cochlear implantation in adults: a multicenter clinical study.

John Arcaroli, Christine Parkinson, Ruth Litovsky … (2006)

To determine the efficacy of "simultaneous" bilateral cochlear implantation (both implants placed during a single surgical procedure) by comparing bilateral and unilateral implant use in a large number of adult subjects tested at multiple sites. Prospective study of 37 adults with postlinguistic onset of bilateral, severe to profound sensorineural hearing loss. Performance with the bilateral cochlear implants, using the same speech processor type and speech processing strategy, was compared with performance using the left implant alone and the right implant alone. Speech understanding in quiet (CNCs and HINT sentences) and in noise (BKB-SIN Test) were evaluated at several postactivation time intervals, with speech presented at 0 degrees azimuth, and noise at either 0 degrees , 90 degrees right, or 90 degrees left in the horizontal plane. APHAB questionnaire data were collected after each subject underwent a 3-wk "bilateral deprivation" period, during which they wore only the speech processor that produced the best score during unilateral testing, and also after a period of listening again with the bilateral implants. By 6-mo postactivation, a significant advantage for speech understanding in quiet was found in the bilateral listening mode compared with either unilateral listening modes. For speech understanding in noise, the largest and most robust bilateral benefit was when the subject was able to take advantage of the head shadow effect; i.e., results were significantly better for bilateral listening compared with the unilateral condition when the ear opposite to the side of the noise was added to create the bilateral condition. This bilateral benefit was seen on at least one of the two unilateral ear comparisons for nearly all (32/34) subjects. Bilateral benefit was also found for a few subjects in spatial configurations that evaluated binaural redundancy and binaural squelch effects. A subgroup of subjects who had asymmetrical unilateral implant performances were, overall, similar in performance to subjects with symmetrical hearing. The questionnaire data indicated that bilateral users perceive their own performance to be better with bilateral cochlear implants than when using a single device. Findings with a large patient group are in agreement with previous reports on smaller groups, showing that, overall, bilateral implantation offers the majority of patients advantages when listening in simulated adverse conditions.

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Speech understanding in background noise with the two-microphone adaptive beamformer BEAM in the Nucleus Freedom Cochlear Implant System.

Ann Spriet, Lieselot Van Deun, Kyriaky Eftaxiadis … (2007)

This paper evaluates the benefit of the two-microphone adaptive beamformer BEAM in the Nucleus Freedom cochlear implant (CI) system for speech understanding in background noise by CI users. A double-blind evaluation of the two-microphone adaptive beamformer BEAM and a hardware directional microphone was carried out with five adult Nucleus CI users. The test procedure consisted of a pre- and post-test in the lab and a 2-wk trial period at home. In the pre- and post-test, the speech reception threshold (SRT) with sentences and the percentage correct phoneme scores for CVC words were measured in quiet and background noise at different signal-to-noise ratios. Performance was assessed for two different noise configurations (with a single noise source and with three noise sources) and two different noise materials (stationary speech-weighted noise and multitalker babble). During the 2-wk trial period at home, the CI users evaluated the noise reduction performance in different listening conditions by means of the SSQ questionnaire. In addition to the perceptual evaluation, the noise reduction performance of the beamformer was measured physically as a function of the direction of the noise source. Significant improvements of both the SRT in noise (average improvement of 5-16 dB) and the percentage correct phoneme scores (average improvement of 10-41%) were observed with BEAM compared to the standard hardware directional microphone. In addition, the SSQ questionnaire and subjective evaluation in controlled and real-life scenarios suggested a possible preference for the beamformer in noisy environments. The evaluation demonstrates that the adaptive noise reduction algorithm BEAM in the Nucleus Freedom CI-system may significantly increase the speech perception by cochlear implantees in noisy listening conditions. This is the first monolateral (adaptive) noise reduction strategy actually implemented in a mainstream commercial CI.

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Author and article information

Contributors

Meni Wanunu: Role: Editor

Journal

Journal ID (nlm-ta): PLoS One

Journal ID (iso-abbrev): PLoS ONE

Journal ID (publisher-id): plos

Journal ID (pmc): plosone

Title: PLoS ONE

Publisher: Public Library of Science (San Francisco, USA )

ISSN (Electronic): 1932-6203

Publication date Collection: 2014

Publication date (Electronic): 22 April 2014

Volume: 9

Issue: 4

Electronic Location Identifier: e95542

Affiliations

[1 ]Department of Otolaryngology, Medical University Hannover, Hannover, Germany

[2 ]Cluster of Excellence hearing4all, Medical University Hannover, Hannover, Germany

[3 ]Advanced Bionics GmbH, European Research Center, Hannover, Germany

Northeastern University, United States of America

Author notes

* E-mail: buechner@ 123456hoerzentrum-hannover.de

Competing Interests: The authors have read the journal's policy and have the following conflicts: One co-author of the manuscript was employed by the MHH using ‘no strings’ funding supplied by Advanced Bionics. Additionally two co-authors hold scientific posts in the Advanced Bionics European Research Centre. The study protocol was developed in close cooperation between MHH and Advanced Bionics. All testing was conducted at MHH by MHH employees and all data were again analyzed in close cooperation between Advanced Bionics and MHH. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.

Conceived and designed the experiments: AB PH SF TL. Performed the experiments: AB KD. Analyzed the data: AB KD PH SF TL. Contributed reagents/materials/analysis tools: KD PH SF. Wrote the paper: AB KD SF PH TL. Preparation of measurement setup: PH SF.

Article

Publisher ID: PONE-D-13-27242

DOI: 10.1371/journal.pone.0095542

PMC ID: 3995709

PubMed ID: 24755864

SO-VID: c0d0ee33-a10c-4b48-b3f2-f2bc0c1b044f

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

History

Date received : 2 July 2013

Date accepted : 27 March 2014

Page count

Pages: 9

Funding

Supported by the EU grant “Europa fördert Niedersachsen” ( http://www.eufoerdert.niedersachsen.de/portal/live.php?navigation_id=5562&article_id=15298&_psmand=18). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Advanced Beamformers for Cochlear Implant Users: Acute Measurement of Speech Perception in Challenging Listening Conditions

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Abstract

Objective

Method

Results

Conclusions

Related collections

PLOS Climate

Most cited references 28

Recognition of speech presented at soft to loud levels by adult cochlear implant recipients of three cochlear implant systems.

Simultaneous bilateral cochlear implantation in adults: a multicenter clinical study.

Speech understanding in background noise with the two-microphone adaptive beamformer BEAM in the Nucleus Freedom Cochlear Implant System.

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