Speech-in-noise intelligibility does not correlate with efferent olivocochlear reflex in humans with normal hearing.
CONCLUSIONS
According to the presented data, speech-in-noise intelligibility (SI) does not correlate with olivocochlear efferent activity - as measured by contralateral suppression (CS) of distortion product otoacoustic emissions (DPOAE) in humans with normal auditory threshold.


OBJECTIVE
Literature data indicate a possible role of the medial olivocochlear efferents in speech intelligibility, especially in background noise. The objective of this study was to investigate this relationship.


METHODS
SI was evaluated in three independent sessions by determining the ratio speech level/noise level, at which 50% of the words are understood (i.e. speech reception threshold, SRT). Efferent activity was inferred measuring CS of DPOAE, using two different paradigms with extensive variation of stimulus parameters and duplicate measurements.


RESULTS
For optimum measurement of CS, the study was restricted to subjects (n =49) with valid DPOAE down to primary tone levels L1=47/L2 =20 dB SPL. Average SRT was -6.66 dB (-4.50 to -7.65 dB, SD 0.63 dB). CS increased with decreasing primary tone levels, with mean absolute CS values in the range of 0.6-6 dB SPL. Test-retest repeatability was good. Statistical evaluation revealed no significant relationship between SI and CS of DPOAE.
Wagner
Wolfgang
W
Tübingen Hearing Research Center, Department of Otolaryngology/Head and Neck Surgery, University of Tübingen, Germany. w.wagner@med.uni-tuebingen.de
Frey
Kathrin
K
Heppelmann
Guido
G
Plontke
Stefan K
SK
Zenner
Hans-Peter
HP
D000328:Adult; D017626:Cochlear Nucleus / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology; D004525:Efferent Pathways / Q000502:physiology; D005260:Female; D006199:Hair Cells, Auditory, Inner / Q000502:physiology; D018072:Hair Cells, Auditory, Outer / Q000502:physiology; D006801:Humans; D008297:Male; D009847:Olivary Nucleus / Q000502:physiology*; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology; D010470:Perceptual Masking / Q000502:physiology*; D012016:Reference Values; D012018:Reflex / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology*; D013069:Speech Reception Threshold Test