Cochlear implants provide hearing to people who are deaf, by electrically stimulating the auditory nerve. Children with a single cochlear implant suffer deficiencies inherent to unilateral hearing, including inability to locate sounds. A second cochlear implant may improve sound localization, which normally requires interpretation of differences in sound intensity and time of arrival between two ears. Currently, it is unknown whether these cues are available to children who were provided with a second cochlear implant after a period of using one implant alone. We asked whether such children could interpret inter-implant level and timing cues. Results indicated that children using two cochlear implants detected level cues but had difficulty interpreting timing cues. Further, children rarely reported that sounds were perceived to come from the middle. Children receiving bilateral cochlear implants sequentially do not process bilateral auditory cues normally but can use inter-implant level cues to make judgments about where sound is coming from.

Cochlear implants provide hearing to people who are deaf, by electrically stimulating the auditory nerve. Children with a single cochlear implant suffer deficiencies inherent to unilateral hearing, including inability to locate sounds. A second cochlear implant may improve sound localization, which normally requires interpretation of differences in sound intensity and time of arrival between two ears. Currently, it is unknown whether these cues are available to children who were provided with a second cochlear implant after a period of using one implant alone. We asked whether such children could interpret inter-implant level and timing cues. Results indicated that children using two cochlear implants detected level cues but had difficulty interpreting timing cues. Further, children rarely reported that sounds were perceived to come from the middle. Children receiving bilateral cochlear implants sequentially do not process bilateral auditory cues normally but can use inter-implant level cues to make judgments about where sound is coming from.

The purpose of the study was to determine whether hearing aids with binaural processing improve performance during a localization and a hearing in noise task. The study included 16 participants, ages 29 – 67, with bilateral, essentially symmetrical, sensorineural hearing loss who had no prior hearing aid experience. Participants were fit with Oticon Epoq XW hearing aids bilaterally and completed the localization and the hearing in noise task with three listening conditions: (1) without hearing aids (NO), (2) with hearing aids that were not linked (BIL), and (3) with hearing aids that were linked (BIN). For the localization task, 1.5 second pink noise bursts at 75 dB SPL were used as the stimulus. A 180° 11-speaker array was set up to the right or left side of the participants. A twelfth speaker on the contralateral side of the array introduced constant background pink noise at 65 dB SPL. Results revealed that participants performed the best with the NO condition, followed by BIL, then BIN. There was a significant difference between NO and BIL and NO and BIN. For the hearing in noise (HIN) task, sentences from the Hearing in Noise Test (HINT) were used as target stimuli. Continuous discourse by one male and two female talkers were used as maskers. There were four masker conditions for this task: (1) signal at 0°, masker at 90° (S0-N90), (2) signal at 0°, masker at 180° (S0-N180), (3) signal at 0°, masker at 270° (S0-N270), and (4) signal at 0°, maskers at 90°, 180°, and 270° (S0-N90, 180, 270). Results revealed that there was no significant difference between listening conditions when all masker conditions were considered. When the one-masker conditions were included, there was a significant difference between the NO and BIL and the NO and BIN conditions with the best performance for BIL, followed by BIN, then NO. Results also revealed a significant difference between masker conditions with the best performance for S0-N270, next best for S0-N90, followed by S0-N180, then S0-N90, 180, 270. / text

Background: Binaural hearing improves our ability to understand speech and to localize sounds. Hearing loss can interfere with binaural cues, and despite the success of amplification, ∼25% of people with bilateral hearing loss fit with two hearing aids choose to wear only one (e.g., Brooks and Bulmer, 1981). One explanation is reduced binaural processing, which occurs when the signal presented to one ear interferes with the perception of the signal presented to the other ear (e.g., Jerger et al, 1993). Typical clinical measures, however, are insensitive to binaural processing deficits. Purpose: The purpose of this study was to determine the extent to which behavioral measures of binaural performance were related to electrophysiological measures of binaural processing in subjects with symmetrical pure-tone sensitivity. Research Design: The relationship between middle latency responses (MLRs) and behavioral performance on binaural listening tasks was assessed by Spearman's rho correlation analyses. Separate repeated measures analyses of variance (RMANOVAs) were performed for MLR latency and MLR amplitude. Study Sample: Nineteen subjects were recruited for the present study based on a clinical presentation of symmetrical pure-tone sensitivity with asymmetrical performance on a word-recognition in noise test. This subpopulation of patients included both subjects with and subjects without hearing loss. Data Collection and Analysis: Monaural and binaural auditory processing was measured behaviorally and electrophysiologically in right-handed subjects. The behavioral tests included the Words-in-Noise test (WIN), the dichotic digits test (DDT), and the 500 Hz masking level difference (MLD). Electrophysiologic responses were measured by the binaural interaction component (BIC) of the MLR. The electrophysiological responses were analyzed to examine the effects of peak (Na, Pa, and Nb) and condition (monaural left, monaural right, binaural, and BIC) on MLR amplitude and latency. Results: Significant correlations were found among electrophysiological measures of binaural hearing and behavioral tests of binaural hearing. A strong correlation between the MLD and the binaural Na-Pa amplitude was found (r =.816). Conclusions: The behavioral and electrophysiological measures used in the present study clearly showed evidence of reduced binaural processing in ∼10 of the subjects in the present study who had symmetrical pure-tone sensitivity. These results underscore the importance of understanding binauralauditory processing and how these measures may or may not identify functional auditory problems.

The objective of the dissertation research is to investigate noise reduction methods for binaural hearing aids based on array and statistical signal processing and inspired by a human auditory model. In digital hearing aids, wide dynamic range compression (WDRC) is the most successful technique to deal with monaural hearing losses. This WDRC processing is usually performed after a monaural noise reduction algorithm. When hearing losses are present in both ears, i.e., a binaural hearing loss, independent monaural hearing aids have been shown not to be comfortable for most users, preferring a processing that involves synchronization between both hearing devices. In addition, psycho-acoustical studies have identified that under hostile environments, e.g., babble noise at very low SNR conditions, users prefer to use linear amplification rather than WDRC. In this sense, the noise reduction algorithm becomes an important component of a digital hearing aid to provide improvement in speech intelligibility and user comfort. Including a wireless link between both hearing aids offers new ways to implement more efficient methods to reduce the background noise and coordinate processing for the two ears. This approach, called binaural hearing aid, has been recently introduced in some commercial products but using very simple processing strategies. This research analyzes the existing binaural noise-reduction techniques, proposes novel perceptually-inspired methods based on blind source separation (BSS) and multichannel Wiener filter (MWF), and identifies different strategies for the real-time implementation of these methods. The proposed methods perform efficient spatial filtering, improve SNR and speech intelligibility, minimize block processing artifacts, and can be implemented in low-power architectures.

No description available.