scholarly journals Sound Source Localization by Normal-Hearing Listeners, Hearing-Impaired Listeners and Cochlear Implant Listeners

2016 ◽  
Vol 21 (3) ◽  
pp. 127-131 ◽  
Author(s):  
Michael F. Dorman ◽  
Louise H. Loiselle ◽  
Sarah J. Cook ◽  
William A. Yost ◽  
René H. Gifford
Keyword(s):  
Cochlear Implant ◽  
Source Localization ◽  
Hearing Aids ◽  
Sound Source ◽  
Hearing Preservation ◽  
Normal Hearing ◽  
Hearing Impaired ◽  
Sound Source Localization ◽  
Localization Accuracy ◽  
Rms Error

Objective: Our primary aim was to determine whether listeners in the following patient groups achieve localization accuracy within the 95th percentile of accuracy shown by younger or older normal-hearing (NH) listeners: (1) hearing impaired with bilateral hearing aids, (2) bimodal cochlear implant (CI), (3) bilateral CI, (4) hearing preservation CI, (5) single-sided deaf CI and (6) combined bilateral CI and bilateral hearing preservation. Design: The listeners included 57 young NH listeners, 12 older NH listeners, 17 listeners fit with hearing aids, 8 bimodal CI listeners, 32 bilateral CI listeners, 8 hearing preservation CI listeners, 13 single-sided deaf CI listeners and 3 listeners with bilateral CIs and bilateral hearing preservation. Sound source localization was assessed in a sound-deadened room with 13 loudspeakers arrayed in a 180-degree arc. Results: The root mean square (rms) error for the NH listeners was 6 degrees. The 95th percentile was 11 degrees. Nine of 16 listeners with bilateral hearing aids achieved scores within the 95th percentile of normal. Only 1 of 64 CI patients achieved a score within that range. Bimodal CI listeners scored at a level near chance, as did the listeners with a single CI or a single NH ear. Listeners with (1) bilateral CIs, (2) hearing preservation CIs, (3) single-sided deaf CIs and (4) both bilateral CIs and bilateral hearing preservation, all showed rms error scores within a similar range (mean scores between 20 and 30 degrees of error). Conclusion: Modern CIs do not restore a normal level of sound source localization for CI listeners with access to sound information from two ears.

scholarly journals Interaural Level Difference Cues Determine Sound Source Localization by Single-Sided Deaf Patients Fit with a Cochlear Implant

2015 ◽  
Vol 20 (3) ◽  
pp. 183-188 ◽  
Author(s):  
Michael F. Dorman ◽  
Daniel Zeitler ◽  
Sarah J. Cook ◽  
Louise Loiselle ◽  
William A. Yost ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Source Localization ◽  
Sound Source ◽  
Low Frequency ◽  
Normal Hearing ◽  
Sound Source Localization ◽  
Interaural Level Difference ◽  
Relative Localization ◽  
Normal Limits ◽  
Single Sided Deafness

In this report, we used filtered noise bands to constrain listeners' access to interaural level differences (ILDs) and interaural time differences (ITDs) in a sound source localization task. The samples of interest were listeners with single-sided deafness (SSD) who had been fit with a cochlear implant in the deafened ear (SSD-CI). The comparison samples included listeners with normal hearing and bimodal hearing, i.e. with a cochlear implant in 1 ear and low-frequency acoustic hearing in the other ear. The results indicated that (i) sound source localization was better in the SSD-CI condition than in the SSD condition, (ii) SSD-CI patients rely on ILD cues for sound source localization, (iii) SSD-CI patients show functional localization abilities within 1-3 months after device activation and (iv) SSD-CI patients show better sound source localization than bimodal CI patients but, on average, poorer localization than normal-hearing listeners. One SSD-CI patient showed a level of localization within normal limits. We provide an account for the relative localization abilities of the groups by reference to the differences in access to ILD cues.

scholarly journals Sound Source Localization by Hearing Preservation Patients with and without Symmetrical Low-Frequency Acoustic Hearing

2015 ◽  
Vol 20 (3) ◽  
pp. 166-171 ◽  
Author(s):  
Louise H. Loiselle ◽  
Michael F. Dorman ◽  
William A. Yost ◽  
René H. Gifford
Keyword(s):  
Source Localization ◽  
Sound Source ◽  
Low Frequency ◽  
Hearing Preservation ◽  
Sound Source Localization ◽  
Localization Accuracy ◽  
Acoustic Hearing ◽  
Low Pass ◽  
Contralateral Ear ◽  
High Pass

The aim of this article was to study sound source localization by cochlear implant (CI) listeners with low-frequency (LF) acoustic hearing in both the operated ear and in the contralateral ear. Eight CI listeners had symmetrical LF acoustic hearing and 4 had asymmetrical LF acoustic hearing. The effects of two variables were assessed: (i) the symmetry of the LF thresholds in the two ears and (ii) the presence/absence of bilateral acoustic amplification. Stimuli consisted of low-pass, high-pass, and wideband noise bursts presented in the frontal horizontal plane. Localization accuracy was 23° of error for the symmetrical listeners and 76° of error for the asymmetrical listeners. The presence of a unilateral CI used in conjunction with bilateral LF acoustic hearing does not impair sound source localization accuracy, but amplification for acoustic hearing can be detrimental to sound source localization accuracy.

scholarly journals Using ILD or ITD Cues for Sound Source Localization and Speech Understanding in a Complex Listening Environment by Listeners With Bilateral and With Hearing-Preservation Cochlear Implants

2016 ◽  
Vol 59 (4) ◽  
pp. 810-818 ◽  
Author(s):  
Louise H. Loiselle ◽  
Michael F. Dorman ◽  
William A. Yost ◽  
Sarah J. Cook ◽  
Rene H. Gifford
Keyword(s):  
Cochlear Implants ◽  
Source Localization ◽  
Sound Source ◽  
Hearing Preservation ◽  
Sound Source Localization ◽  
Speech Understanding ◽  
Cocktail Party ◽  
Localization Accuracy ◽  
Low Pass ◽  
High Pass

PurposeTo assess the role of interaural time differences and interaural level differences in (a) sound-source localization, and (b) speech understanding in a cocktail party listening environment for listeners with bilateral cochlear implants (CIs) and for listeners with hearing-preservation CIs.MethodsEleven bilateral listeners with MED-EL (Durham, NC) CIs and 8 listeners with hearing-preservation CIs with symmetrical low frequency, acoustic hearing using the MED-EL or Cochlear device were evaluated using 2 tests designed to task binaural hearing, localization, and a simulated cocktail party. Access to interaural cues for localization was constrained by the use of low-pass, high-pass, and wideband noise stimuli.ResultsSound-source localization accuracy for listeners with bilateral CIs in response to the high-pass noise stimulus and sound-source localization accuracy for the listeners with hearing-preservation CIs in response to the low-pass noise stimulus did not differ significantly. Speech understanding in a cocktail party listening environment improved for all listeners when interaural cues, either interaural time difference or interaural level difference, were available.ConclusionsThe findings of the current study indicate that similar degrees of benefit to sound-source localization and speech understanding in complex listening environments are possible with 2 very different rehabilitation strategies: the provision of bilateral CIs and the preservation of hearing.

scholarly journals Sound source localization of filtered noises by listeners with normal hearing: A statistical analysis

2013 ◽  
Vol 133 (5) ◽  
pp. 2876-2882 ◽  
Author(s):  
William A. Yost ◽  
Louise Loiselle ◽  
Michael Dorman ◽  
Jason Burns ◽  
Christopher A. Brown
Keyword(s):  
Statistical Analysis ◽  
Source Localization ◽  
Sound Source ◽  
Normal Hearing ◽  
Sound Source Localization

Noise-Robust MUSIC-Based Sound Source Localization Using Steering Vector Transformation for Small Humanoids

2017 ◽  
Vol 29 (1) ◽  
pp. 26-36 ◽  
Author(s):  
Ryu Takeda ◽  
◽  
Kazunori Komatani
Keyword(s):  
Source Localization ◽  
Sound Source ◽  
Computational Cost ◽  
Internal Noise ◽  
Humanoid Robots ◽  
Eigenvalue Decomposition ◽  
Sound Source Localization ◽  
Noise Robustness ◽  
Localization Accuracy ◽  
Steering Vector

[abstFig src='/00290001/03.jpg' width='300' text='Sound source localization and problem' ] We focus on the problem of localizing soft/weak voices recorded by small humanoid robots, such as NAO. Sound source localization (SSL) for such robots requires fast processing and noise robustness owing to the restricted resources and the internal noise close to the microphones. Multiple signal classification using generalized eigenvalue decomposition (GEVD-MUSIC) is a promising method for SSL. It achieves noise robustness by whitening robot internal noise using prior noise information. However, whitening increases the computational cost and creates a direction-dependent bias in the localization score, which degrades the localization accuracy. We have thus developed a new implementation of GEVD-MUSIC based on steering vector transformation (TSV-MUSIC). The application of a transformation equivalent to whitening to steering vectors in advance reduces the real-time computational cost of TSV-MUSIC. Moreover, normalization of the transformed vectors cancels the direction-dependent bias and improves the localization accuracy. Experiments using simulated data showed that TSV-MUSIC had the highest accuracy of the methods tested. An experiment using real recoded data showed that TSV-MUSIC outperformed GEVD-MUSIC and other MUSIC methods in terms of localization by about 4 points under low signal-to-noise-ratio conditions.

scholarly journals Sound Localization Bias and Error in Bimodal Listeners Improve Instantaneously When the Device Delay Mismatch Is Reduced

2021 ◽  
Vol 25 ◽  
pp. 233121652110161
Author(s):  
Julian Angermeier ◽  
Werner Hemmert ◽  
Stefan Zirn
Keyword(s):  
Sound Localization ◽  
Source Localization ◽  
Sound Source ◽  
Travelling Wave ◽  
Nerve Fibers ◽  
Sound Source Localization ◽  
Localization Accuracy ◽  
Contralateral Ear ◽  
Processing Delay ◽  
Interaural Time Delay

Users of a cochlear implant (CI) in one ear, who are provided with a hearing aid (HA) in the contralateral ear, so-called bimodal listeners, are typically affected by a constant and relatively large interaural time delay offset due to differences in signal processing and differences in stimulation. For HA stimulation, the cochlear travelling wave delay is added to the processing delay, while for CI stimulation, the auditory nerve fibers are stimulated directly. In case of MED-EL CI systems in combination with different HA types, the CI stimulation precedes the acoustic HA stimulation by 3 to 10 ms. A self-designed, battery-powered, portable, and programmable delay line was applied to the CI to reduce the device delay mismatch in nine bimodal listeners. We used an A-B-B-A test design and determined if sound source localization improves when the device delay mismatch is reduced by delaying the CI stimulation by the HA processing delay (τHA). Results revealed that every subject in our group of nine bimodal listeners benefited from the approach. The root-mean-square error of sound localization improved significantly from 52.6° to 37.9°. The signed bias also improved significantly from 25.2° to 10.5°, with positive values indicating a bias toward the CI. Furthermore, two other delay values (τHA –1 ms and τHA +1 ms) were applied, and with the latter value, the signed bias was further reduced in some test subjects. We conclude that sound source localization accuracy in bimodal listeners improves instantaneously and sustainably when the device delay mismatch is reduced.

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