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We develop an objective, noninvasive method for determining the frequency selectivity of cochlear tuning at low and moderate sound levels. Applicable in humans at frequencies of 1 kHz and above, the method is based on the measurement of stimulus-frequency otoacoustic emissions and, unlike previous noninvasive physiological methods, does not depend on the(More)
Otoacoustic emissions (OAEs) of all types are widely assumed to arise by a common mechanism: nonlinear electromechanical distortion within the cochlea. In this view, both stimulus-frequency (SFOAEs) and distortion-product emissions (DPOAEs) arise because nonlinearities in the mechanics act as "sources" of backward-traveling waves. This unified picture is(More)
This review covers the basic anatomy and physiology of the olivocochlear reflexes and the use of otoacoustic emissions (OAEs) in humans to monitor the effects of one group, the medial olivocochlear (MOC) efferents. MOC fibers synapse on outer hair cells (OHCs), and activation of these fibers inhibits basilar membrane responses to low-level sounds. This(More)
Tinnitus, the perception of sound in the absence of external stimuli, is a common and often disturbing symptom that is not understood physiologically. This paper presents an approach for using functional magnetic resonance imaging (fMRI) to investigate the physiology of tinnitus and demonstrates that the approach is effective in revealing tinnitus-related(More)
In the medial nucleus of the trapezoid body (MNTB), each principal neuron receives one large axonal ending (a calyx of Held) and many small endings. In this same region, microelectrode recordings show unusual 'unit' waveforms which have two components separated by about 0.5 ms. We show that the first component (C1) of such a waveform corresponds to a spike(More)
  • John J Guinan
  • 2010
PURPOSE OF REVIEW This review covers topics relevant to olivocochlear-efferent anatomy and function for which there are new findings in papers from 2009 to early 2010. RECENT FINDINGS Work within the review period has increased our understanding of medial olivocochlear (MOC) mechanisms in outer hair cells, MOC-reflex tuning, MOC effects on distortion(More)
An anterograde tracer (35S-methionine) was injected unilaterally in the superior olivary complex (SOC) at regions previously demonstrated by retrograde labeling to contain olivocochlear (OC) cell bodies. Quantitative analysis of cochlear autoradiographs from these cats demonstrates that there are two OC systems. The lateral OC system has cell bodies lateral(More)
Otoacoustic emissions (OAEs) are useful for studying medial olivocochlear (MOC) efferents, but several unresolved methodological issues cloud the interpretation of the data they produce. Most efferent assays use a "probe stimulus" to produce an OAE and an "elicitor stimulus" to evoke efferent activity and thereby change the OAE. However, little attention(More)
This paper tests and applies a key prediction of the theory of coherent reflection filtering for the generation of reflection-source otoacoustic emissions. The theory predicts that reflection-source-emission group delay is determined by the group delay of the basilar-membrane (BM) transfer function at its peak. This prediction is tested over a seven-octave(More)