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Ignatious E, Azam S, Jonkman M, De Boer F. Binaural masking level difference for pure tone signals. J Otol 2023; 18:160-167. [PMID: 37497326 PMCID: PMC10366637 DOI: 10.1016/j.joto.2023.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Accepted: 06/11/2023] [Indexed: 07/28/2023] Open
Abstract
The binaural masking level difference (BMLD) is a psychoacoustic method to determine binaural interaction and central auditory processes. The BMLD is the difference in hearing thresholds in homophasic and antiphasic conditions. The duration, phase and frequency of the stimuli can affect the BMLD. The main aim of the study is to evaluate the BMLD for stimuli of different durations and frequencies which could also be used in future electrophysiological studies. To this end we developed a GUI to present different frequency signals of variable duration and determine the BMLD. Three different durations and five different frequencies are explored. The results of the study confirm that the hearing threshold for the antiphasic condition is lower than the hearing threshold for the homophasic condition and that differences are significant for signals of 18ms and 48ms duration. Future objective binaural processing studies will be based on 18ms and 48ms stimuli with the same frequencies as used in the current study.
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Xu N, Luo L, Chen L, Ding Y, Li L. Different binaural processing of the envelope component and the temporal fine structure component of a narrowband noise in rat inferior colliculus. Hear Res 2021; 411:108354. [PMID: 34583218 DOI: 10.1016/j.heares.2021.108354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/29/2021] [Accepted: 09/15/2021] [Indexed: 11/18/2022]
Abstract
Complex broadband sounds are decomposed by peripheral auditory filters into a series of relatively narrowband signals, each with a slowly varying envelope (ENV) and a rapidly fluctuating temporal fine structure (TFS). ENV and TFS information at the bilateral ears contribute differentially to auditory perception. However, whether the difference could attribute to mechanisms of binaural integration remains an open question. As a potential neural correlate, subsets of neurons in the central nucleus of the inferior colliculus (ICC) are known to integrate binaural information with binaural inhibition or binaural summation. Therefore, we recorded the frequency-following responses (FFRs) to the ENV and TFS components of narrowband noises in the ICC of anesthetized rats and examined changes in FFR amplitude and stimulus-response coherence under various sound-delivery settings. We showed that binaural FFRENV was predominantly elicited by contralateral inputs and inhibited by ipsilateral inputs, exhibiting a "binaural-inhibition" like property. On the other hand, binaural FFRTFS received a balanced contribution from both sides, echoing the "binaural-summation" mechanism. What is more, binaural FFRENV was significantly correlated with contralateral-evoked but not ipsilateral-evoked FFRENV, while binaural FFRTFS correlated with both contralateral- and ipsilateral-evoked FFRTFS. Overall, these results suggest distinct binaural processing of ENV and TFS information at the midbrain level.
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Affiliation(s)
- Na Xu
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100080, China; Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China.
| | - Lu Luo
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100080, China; School of Psychology, Beijing Sport University, Beijing 100084, China
| | - Liangjie Chen
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100080, China
| | - Yu Ding
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100080, China; Division of Sports Science and physical education, Tsinghua University, Beijing 100084, China
| | - Liang Li
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing 100080, China; Speech and Hearing Research Center, Key Laboratory on Machine Perception (Ministry of Education), Peking University, Beijing 100871, China; Beijing Institute for Brain Disorders, Beijing 100096, China.
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Luo L, Xu N, Wang Q, Li L. Disparity in interaural time difference improves the accuracy of neural representations of individual concurrent narrowband sounds in rat inferior colliculus and auditory cortex. J Neurophysiol 2020; 123:695-706. [PMID: 31891521 DOI: 10.1152/jn.00284.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The central mechanisms underlying binaural unmasking for spectrally overlapping concurrent sounds, which are unresolved in the peripheral auditory system, remain largely unknown. In this study, frequency-following responses (FFRs) to two binaurally presented independent narrowband noises (NBNs) with overlapping spectra were recorded simultaneously in the inferior colliculus (IC) and auditory cortex (AC) in anesthetized rats. The results showed that for both IC FFRs and AC FFRs, introducing an interaural time difference (ITD) disparity between the two concurrent NBNs enhanced the representation fidelity, reflected by the increased coherence between the responses evoked by double-NBN stimulation and the responses evoked by single NBNs. The ITD disparity effect varied across frequency bands, being more marked for higher frequency bands in the IC and lower frequency bands in the AC. Moreover, the coherence between IC responses and AC responses was also enhanced by the ITD disparity, and the enhancement was most prominent for low-frequency bands and the IC and the AC on the same side. These results suggest a critical role of the ITD cue in the neural segregation of spectrotemporally overlapping sounds.NEW & NOTEWORTHY When two spectrally overlapped narrowband noises are presented at the same time with the same sound-pressure level, they mask each other. Introducing a disparity in interaural time difference between these two narrowband noises improves the accuracy of the neural representation of individual sounds in both the inferior colliculus and the auditory cortex. The lower frequency signal transformation from the inferior colliculus to the auditory cortex on the same side is also enhanced, showing the effect of binaural unmasking.
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Affiliation(s)
- Lu Luo
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, China
| | - Na Xu
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, China
| | - Qian Wang
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, China.,Beijing Key Laboratory of Epilepsy, Epilepsy Center, Department of Functional Neurosurgery, Sanbo Brain Hospital, Capital Medical University, Beijing, China
| | - Liang Li
- School of Psychological and Cognitive Sciences, Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, China.,Speech and Hearing Research Center, Key Laboratory on Machine Perception (Ministry of Education), Peking University, Beijing, China.,Beijing Institute for Brain Disorders, Beijing, China
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