Background:The activation of the medial olivocochlear reflex reduces the cochlear gain,which is manifested perceptually as decreased auditory sensitivity.However,it has remained unclear whether the extent of this supp...Background:The activation of the medial olivocochlear reflex reduces the cochlear gain,which is manifested perceptually as decreased auditory sensitivity.However,it has remained unclear whether the extent of this suppression varies according to the cochlear region involved.Here we aims to assess the magnitude of contralateral efferent suppression across human cochlea,at low levels,and its impact on hearing sensitivity.Methods:Assuming that acoustic stimulation activates the contralateral medial olivocochlear reflex,we evaluated the magnitude of the suppressive effect as a function of frequency in 17 subjects with normal hearing.Absolute thresholds were measured for bursts tones of various durations(10,100,and 500 ms)and frequencies(250,500,1000,4000,and 8000 Hz)in the presence or absence of contralateral white noise at 60 d B SPL.Results:We found that contralateral noise raised the absolute threshold for the burst tones evaluated.The effect was greater at lower than higher frequencies(3.85 d B at 250 Hz vs.2.22 d B at 8000 Hz).Conclusions:Our findings suggest that in humans,the magnitude of this suppression varies according to the cochlear region stimulated,with a greater effect towards the apex(lower frequencies)than the base(higher frequencies)of the cochlea.展开更多
Previous research has demonstrated that the amplitude of evoked emissions decreases in human sub-jects when the contralateral ear is stimulated by noise. The medial olivocochlear bundle (MOCB) is be-lieved to control ...Previous research has demonstrated that the amplitude of evoked emissions decreases in human sub-jects when the contralateral ear is stimulated by noise. The medial olivocochlear bundle (MOCB) is be-lieved to control this phenomenon. Recent research has examined this effect in individuals with auditory pro-cessing disorders (APD), specifically with difficulty understanding speech in noise. Results showed tran-sient evoked otoacoustic emissions (TEOAEs) were not affected by contralateral stimulation in these sub-jects. Much clinical research has measured the function of the MOCB through TEOAEs.This study will use an alternative technique, distortion product otoacoustic emissions (DPOAEs), to examine this phenomenon and evaluate the function of the MOCB. DPOAEs of individuals in a control group with normal hearing and no significant auditory processing difficulties were compared to the DPOAEs of children with signifi-cant auditory processing difficulties.Results showed that the suppression effect was observed in the control group at 2 kHz with 3 kHz of narrowband noise. For the auditory processing disorders group, no significant suppression was observed.Overall, DPOAEs showed suppression with contralateral noise, while the APD group levels increased overall.These results provide further evidence that the MOCB may have reduced function in children with APD.展开更多
基金Work supported by a grant of the University of Chile(UI-10/16)to EA。
文摘Background:The activation of the medial olivocochlear reflex reduces the cochlear gain,which is manifested perceptually as decreased auditory sensitivity.However,it has remained unclear whether the extent of this suppression varies according to the cochlear region involved.Here we aims to assess the magnitude of contralateral efferent suppression across human cochlea,at low levels,and its impact on hearing sensitivity.Methods:Assuming that acoustic stimulation activates the contralateral medial olivocochlear reflex,we evaluated the magnitude of the suppressive effect as a function of frequency in 17 subjects with normal hearing.Absolute thresholds were measured for bursts tones of various durations(10,100,and 500 ms)and frequencies(250,500,1000,4000,and 8000 Hz)in the presence or absence of contralateral white noise at 60 d B SPL.Results:We found that contralateral noise raised the absolute threshold for the burst tones evaluated.The effect was greater at lower than higher frequencies(3.85 d B at 250 Hz vs.2.22 d B at 8000 Hz).Conclusions:Our findings suggest that in humans,the magnitude of this suppression varies according to the cochlear region stimulated,with a greater effect towards the apex(lower frequencies)than the base(higher frequencies)of the cochlea.
文摘Previous research has demonstrated that the amplitude of evoked emissions decreases in human sub-jects when the contralateral ear is stimulated by noise. The medial olivocochlear bundle (MOCB) is be-lieved to control this phenomenon. Recent research has examined this effect in individuals with auditory pro-cessing disorders (APD), specifically with difficulty understanding speech in noise. Results showed tran-sient evoked otoacoustic emissions (TEOAEs) were not affected by contralateral stimulation in these sub-jects. Much clinical research has measured the function of the MOCB through TEOAEs.This study will use an alternative technique, distortion product otoacoustic emissions (DPOAEs), to examine this phenomenon and evaluate the function of the MOCB. DPOAEs of individuals in a control group with normal hearing and no significant auditory processing difficulties were compared to the DPOAEs of children with signifi-cant auditory processing difficulties.Results showed that the suppression effect was observed in the control group at 2 kHz with 3 kHz of narrowband noise. For the auditory processing disorders group, no significant suppression was observed.Overall, DPOAEs showed suppression with contralateral noise, while the APD group levels increased overall.These results provide further evidence that the MOCB may have reduced function in children with APD.
