Auditory Efferents Facilitate Sound Localization in Noise in Humans

The mammalian auditory system contains descending neural pathways, some of which project onto the cochlea via the medial olivocochlear (MOC) system. The function of this efferent auditory system is not entirely clear. Behavioral studies in animals with olivocochlear (OC) lesions suggest that the MOC serves to facilitate sound localization in noise. In the current work, noise-induced OC activity (the OC reflex) and sound-localization performance in noise were measured in normal-hearing humans. Consistent with earlier studies, both measures were found to vary substantially across individuals. Importantly, significant correlations were observed between OC-reflex strength and the effect of noise on sound-localization performance; the stronger the OC reflex, the less marked the effect of noise. These results suggest that MOC activation by noise helps to counteract the detrimental effects of background noise on neural representations of direction-dependent spectral features, which are especially important for accurate localization in the up/down and front/back dimensions.

[1]  D M Green,et al.  Probability of being correct with 1 ofM orthogonal signals , 1991, Perception & psychophysics.

[2]  J. Guinan,et al.  Effects of crossed-olivocochlear-bundle stimulation on cat auditory nerve fiber responses to tones. , 1983, The Journal of the Acoustical Society of America.

[3]  François Mauguière,et al.  Evidence for corticofugal modulation of peripheral auditory activity in humans. , 2006, Cerebral cortex.

[4]  Lina A. J. Reiss,et al.  Effects of Signal Level and Background Noise on Spectral Representations in the Auditory Nerve of the Domestic Cat , 2011, Journal of the Association for Research in Otolaryngology.

[5]  L. Collet,et al.  Is the test of medial efferent system function a relevant investigation in tinnitus? , 1994, British journal of audiology.

[6]  Riitta Hari,et al.  Human cortical representation of virtual auditory space: differences between sound azimuth and elevation , 2002, The European journal of neuroscience.

[7]  J. Guinan.  Olivocochlear Efferents: Anatomy, Physiology, Function, and the Measurement of Efferent Effects in Humans , 2006, Ear and hearing.

[8]  J. H. Dewson,et al.  sone relationships to stimulus discrimination in noise. , 1968, Journal of neurophysiology.

[9]  T Kawase,et al.  Antimasking effects of the olivocochlear reflex. II. Enhancement of auditory-nerve response to masked tones. , 1993, Journal of neurophysiology.

[10]  André van Schaik,et al.  Auditory spatial perception with sources overlapping in frequency and time , 2005 .

[11]  R. C. Oldfield.  The assessment and analysis of handedness: the Edinburgh inventory. , 1971, Neuropsychologia.

[12]  John K Niparko,et al.  Behavioral studies of the olivocochlear efferent system: learning to listen in noise. , 2004, Archives of otolaryngology--head & neck surgery.

[13]  E. Buss,et al.  The function(s) of the medial olivocochlear efferent system in hearing , 2005 .

[14]  R. Zatorre,et al.  Where is 'where' in the human auditory cortex? , 2002, Nature Neuroscience.

[15]  D. M. Green,et al.  Sound localization by human listeners. , 1991, Annual review of psychology.

[16]  S. Khalfa,et al.  Influence of handedness on peripheral auditory asymmetry , 1998, The European journal of neuroscience.

[17]  R. Ruben,et al.  Inhibition of Central Auditory Response , 1960, Science.

[18]  J. C. Middlebrooks,et al.  Localization of brief sounds: effects of level and background noise. , 2000, The Journal of the Acoustical Society of America.

[19]  D. M. Green,et al.  Signal detection theory and psychophysics , 1966 .

[20]  I. Russell,et al.  The effect of efferent stimulation on basilar membrane displacement in the basal turn of the guinea pig cochlea , 1996, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[21]  G L Romani,et al.  Human brain activation during passive listening to sounds from different locations: An fMRI and MEG study , 2005, Human brain mapping.

[22]  C. Lorenzi,et al.  Sound localization in noise in normal-hearing listeners. , 1997, The Journal of the Acoustical Society of America.

[23]  A. Thornton,et al.  Neural Correlates of Perceptual Learning in the Auditory Brainstem: Efferent Activity Predicts and Reflects Improvement at a Speech-in-Noise Discrimination Task , 2008, The Journal of Neuroscience.

[24]  John J. Guinan,et al.  Measurement of the Distribution of Medial Olivocochlear Acoustic Reflex Strengths Across Normal-Hearing Individuals via Otoacoustic Emissions , 2007, Journal of the Association for Research in Otolaryngology.

[25]  R. Gilkey,et al.  Sound localization in noise: the effect of signal-to-noise ratio. , 1996, The Journal of the Acoustical Society of America.

[26]  L Collet,et al.  Involvement of the olivocochlear bundle in the detection of tones in noise. , 1996, The Journal of the Acoustical Society of America.

[27]  F A Wichmann,et al.  Ning for Helpful Comments and Suggestions. This Paper Benefited Con- Siderably from Conscientious Peer Review, and We Thank Our Reviewers the Psychometric Function: I. Fitting, Sampling, and Goodness of Fit , 2001 .

[28]  T Morlet,et al.  Development of human cochlear active mechanism asymmetry: involvement of the medial olivocochlear system? , 1999, Hearing Research.

[29]  B. Cone-Wesson,et al.  Asymmetric Cochlear Processing Mimics Hemispheric Specialization , 2004, Science.

[30]  M. Sachs,et al.  Effect of electrical stimulation of the crossed olivocochlear bundle on auditory nerve response to tones in noise. , 1987, Journal of neurophysiology.