scholarly journals Spatial Release From Masking in Adults With Bilateral Cochlear Implants: Effects of Distracter Azimuth and Microphone Location

2018 ◽  
Vol 61 (3) ◽  
pp. 752-761 ◽  
Author(s):  
Timothy J. Davis ◽  
René H. Gifford
Keyword(s):  
Cochlear Implants ◽  
Spatial Configuration ◽  
Block Design ◽  
Speech Understanding ◽  
Traditional Assessment ◽  
Bilateral Cochlear Implants ◽  
Secondary Purpose ◽  
Spatial Release ◽  
Bilateral Cochlear Implant ◽  
Release From Masking

PurposeThe primary purpose of this study was to derive spatial release from masking (SRM) performance-azimuth functions for bilateral cochlear implant (CI) users to provide a thorough description of SRM as a function of target/distracter spatial configuration. The secondary purpose of this study was to investigate the effect of the microphone location for SRM in a within-subject study design.MethodSpeech recognition was measured in 12 adults with bilateral CIs for 11 spatial separations ranging from −90° to +90° in 20° steps using an adaptive block design. Five of the 12 participants were tested with both the behind-the-ear microphones and a T-mic configuration to further investigate the effect of mic location on SRM.ResultsSRM can be significantly affected by the hemifield origin of the distracter stimulus—particularly for listeners with interaural asymmetry in speech understanding. The greatest SRM was observed with a distracter positioned 50° away from the target. There was no effect of mic location on SRM for the current experimental design.ConclusionOur results demonstrate that the traditional assessment of SRM with a distracter positioned at 90° azimuth may underestimate maximum performance for individuals with bilateral CIs.

Binaural Speech Understanding With Bilateral Cochlear Implants in Reverberation

2018 ◽  
Vol 27 (1) ◽  
pp. 85-94 ◽  
Author(s):  
Kostas Kokkinakis
Keyword(s):  
Sound Field ◽  
Spatial Location ◽  
Speech Understanding ◽  
Spatial Cues ◽  
Bilateral Cochlear Implants ◽  
Positive Effects ◽  
Spatial Release ◽  
Listening Environments ◽  
Speech Reception Thresholds ◽  
Release From Masking

PurposeThe purpose of this study was to investigate whether bilateral cochlear implant (CI) listeners who are fitted with clinical processors are able to benefit from binaural advantages under reverberant conditions. Another aim of this contribution was to determine whether the magnitude of each binaural advantage observed inside a highly reverberant environment differs significantly from the magnitude measured in a near-anechoic environment.MethodTen adults with postlingual deafness who are bilateral CI users fitted with either Nucleus 5 or Nucleus 6 clinical sound processors (Cochlear Corporation) participated in this study. Speech reception thresholds were measured in sound field and 2 different reverberation conditions (0.06 and 0.6 s) as a function of the listening condition (left, right, both) and the noise spatial location (left, front, right).ResultsThe presence of the binaural effects of head-shadow, squelch, summation, and spatial release from masking in the 2 different reverberation conditions tested was determined using nonparametric statistical analysis. In the bilateral population tested, when the ambient reverberation time was equal to 0.6 s, results indicated strong positive effects of head-shadow and a weaker spatial release from masking advantage, whereas binaural squelch and summation contributed no statistically significant benefit to bilateral performance under this acoustic condition. These findings are consistent with those of previous studies, which have demonstrated that head-shadow yields the most pronounced advantage in noise. The finding that spatial release from masking produced little to almost no benefit in bilateral listeners is consistent with the hypothesis that additive reverberation degrades spatial cues and negatively affects binaural performance.ConclusionsThe magnitude of 4 different binaural advantages was measured on the same group of bilateral CI subjects fitted with clinical processors in 2 different reverberation conditions. The results of this work demonstrate the impeding properties of reverberation on binaural speech understanding. In addition, results indicate that CI recipients who struggle in everyday listening environments are also more likely to benefit less in highly reverberant environments from their bilateral processors.

scholarly journals Spatial Release From Informational and Energetic Masking in Bimodal and Bilateral Cochlear Implant Users

2020 ◽  
Vol 63 (11) ◽  
pp. 3816-3833
Author(s):  
Kristen D'Onofrio ◽  
Virginia Richards ◽  
René Gifford
Keyword(s):  
Cochlear Implant ◽  
Statistical Significance ◽  
Spatial Separation ◽  
Correlated Noise ◽  
Speech Understanding ◽  
Informational Masking ◽  
Spatial Release ◽  
Spatial Configurations ◽  
Bilateral Cochlear Implant ◽  
Release From Masking

Purpose Spatially separating speech and background noise improves speech understanding in normal-hearing listeners, an effect referred to as spatial release from masking (SRM). In cochlear implant (CI) users, SRM has often been demonstrated using asymmetric noise configurations, which maximize benefit from head shadow and the potential availability of binaural cues. In contrast, SRM in symmetrical configurations has been minimal to absent in CI users. We examined the interaction between two types of maskers (informational and energetic) and SRM in bimodal and bilateral CI users. We hypothesized that SRM would be absent or “negative” using symmetrically separated noise maskers. Second, we hypothesized that bimodal listeners would exhibit greater release from informational masking due to access to acoustic information in the non-CI ear. Method Participants included 10 bimodal and 10 bilateral CI users. Speech understanding in noise was tested in 24 conditions: 3 spatial configurations (S 0 N 0 , S 0 N 45&315 , S 0 N 90&270 ) × 2 masker types (speech, signal-correlated noise) × 2 listening configurations (best-aided, CI-alone) × 2 talker gender conditions (different-gender, same-gender). Results In support of our first hypothesis, both groups exhibited negative SRM with increasing spatial separation. In opposition to our second hypothesis, both groups exhibited similar magnitudes of release from informational masking. The magnitude of release was greater for bimodal listeners, though this difference failed to reach statistical significance. Conclusions Both bimodal and bilateral CI recipients exhibited negative SRM. This finding is consistent with CI signal processing limitations, the audiologic factors associated with SRM, and known effects of behind-the-ear microphone technology. Though release from informational masking was not significantly different across groups, the magnitude of release was greater for bimodal listeners. This suggests that bimodal listeners may be at least marginally more susceptible to informational masking than bilateral CI users, though further research is warranted.

scholarly journals The Effect of Simulated Interaural Frequency Mismatch on Speech Understanding and Spatial Release From Masking

2018 ◽  
Vol 39 (5) ◽  
pp. 895-905 ◽  
Author(s):  
Matthew J. Goupell ◽  
Corey A. Stoelb ◽  
Alan Kan ◽  
Ruth Y. Litovsky
Keyword(s):  
Speech Understanding ◽  
Frequency Mismatch ◽  
Spatial Release ◽  
Release From Masking
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