Boothalingam Sriram, Purcell David W
National Centre for Audiology, Western University, London, Ontario N6G 1H1, Canada.
J Acoust Soc Am. 2015 Feb;137(2):724-32. doi: 10.1121/1.4906250.
Click evoked otoacoustic emissions (CEOAEs) are commonly used both in research and clinics to assay the medial olivocochlear system (MOC). Clicks presented at rates >50 Hz in the contralateral ear have previously been reported to evoke contralateral MOC activity. However, in typical MOC assays, clicks are presented in the ipsilateral ear in conjunction with MOC elicitor (noise) in the contralateral ear. The effect of click rates in such an arrangement is currently unknown. A forward masking paradigm was used to emulate typical MOC assays to elucidate the influence of ipsilateral click presentation rates on MOC inhibition of CEOAEs in 28 normal hearing adults. Influence of five click rates (20.83, 25, 31.25, 41.67, and 62.5 Hz) presented at 55 dB peSPL was tested. Results indicate that click rates as low as 31.25 Hz significantly enhance contralateral MOC inhibition, possibly through the activation of ipsilateral and binaural MOC neurons with potential contributions from the middle ear muscle reflex. Therefore, click rates ≤25 Hz are recommended for use in MOC assays, at least for 55 dB peSPL click level.
瞬态诱发耳声发射（CEOAEs）在研究和临床中常用于检测内侧橄榄耳蜗系统（MOC）。先前有报道称，对侧耳以>50 Hz的速率呈现的瞬态声可诱发对侧MOC活动。然而，在典型的MOC检测中，瞬态声在同侧耳呈现，同时在对侧耳呈现MOC激发声（噪声）。目前尚不清楚这种安排下瞬态声速率的影响。采用前掩蔽范式来模拟典型的MOC检测，以阐明同侧瞬态声呈现速率对28名正常听力成年人中MOC对CEOAEs抑制作用的影响。测试了在55 dB peSPL下呈现的五种瞬态声速率（20.83、25、31.25、41.67和62.5 Hz）的影响。结果表明，低至31.25 Hz的瞬态声速率可显著增强对侧MOC抑制作用，可能是通过激活同侧和双耳MOC神经元，并可能有中耳肌肉反射的作用。因此，建议在MOC检测中使用≤25 Hz的瞬态声速率，至少对于55 dB peSPL的瞬态声水平如此。
