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Transient Evoked Otoacoustic Emissions Recorded Using Maximum Length Sequences as a Function of Stimulus Rate and Level

 

作者: Jemma Hine,   A. Roger Thornton,  

 

期刊: Ear and Hearing  (OVID Available online 1997)
卷期: Volume 18, issue 2  

页码: 121-128

 

ISSN:0196-0202

 

年代: 1997

 

出版商: OVID

 

数据来源: OVID

 

摘要:

Objective:The recently developed technique of recording transient evoked otoacoustic emissions (TEOAEs) using clicks presented according to maximum length sequences (MLSs) enables very high stimulation rates to be used. The aim of this study was to provide normative data on the relationship between TEOAEs recorded conventionally (at 40 clicks/sec) and those recorded using the MLS technique (at 11 maximum rates between 100 and 5000 clicks/sec) to establish a baseline for future clinical studies.Design:TEOAEs were recorded at 12 rates from 12 normally hearing adult ears at click levels decreasing in 5 dB steps from 68 dB peSPL.Results:The morphology of the waveforms and the pattern of the input/output functions with latency were similar for conventional and MLS TEOAEs. The only major difference between TEOAEs recorded at the different rates was in their absolute amplitude. As the click rate was increased from 40 clicks/sec there was a reduction in amplitude that reached a near asymptote at approximately 1500 clicks/sec. When expressed as a percentage reduction in amplitude compared with that recorded at 40 clicks/sec, this MLS "rate effect" was independent of stimulus level over all but the lowest test level (38 dB peSPL).Conclusion:Over a wide range of amplitudes of conventionally recorded TEOAEs (21 to 450 µPa for the 9 to 13 msec section of the otoacoustic emission), the mechanism involved in the MLS rate effect seems to act in a way that reduces the amplitude by an almost constant proportion, whatever its original size.

 



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