人工耳蜗使用者的前掩蔽空间调谐曲线。
Forward-masked spatial tuning curves in cochlear implant users.
作者信息
Nelson David A, Donaldson Gail S, Kreft Heather
机构信息
Clinical Psychoacoustics Laboratory, Department of Otolaryngology, University of Minnesota, MMC396, 420 Delaware Street S.E., Minneapolis, Minnesota 55455, USA.
出版信息
J Acoust Soc Am. 2008 Mar;123(3):1522-43. doi: 10.1121/1.2836786.
Forward-masked psychophysical spatial tuning curves (fmSTCs) were measured in twelve cochlear-implant subjects, six using bipolar stimulation (Nucleus devices) and six using monopolar stimulation (Clarion devices). fmSTCs were measured at several probe levels on a middle electrode using a fixed-level probe stimulus and variable-level maskers. The average fmSTC slopes obtained in subjects using bipolar stimulation (3.7 dBmm) were approximately three times steeper than average slopes obtained in subjects using monopolar stimulation (1.2 dBmm). Average spatial bandwidths were about half as wide for subjects with bipolar stimulation (2.6 mm) than for subjects with monopolar stimulation (4.6 mm). None of the tuning curve characteristics changed significantly with probe level. fmSTCs replotted in terms of acoustic frequency, using Greenwood's [J. Acoust. Soc. Am. 33, 1344-1356 (1961)] frequency-to-place equation, were compared with forward-masked psychophysical tuning curves obtained previously from normal-hearing and hearing-impaired acoustic listeners. The average tuning characteristics of fmSTCs in electric hearing were similar to the broad tuning observed in normal-hearing and hearing-impaired acoustic listeners at high stimulus levels. This suggests that spatial tuning is not the primary factor limiting speech perception in many cochlear implant users.
在12名人工耳蜗受试者中测量了前掩蔽心理物理空间调谐曲线（fmSTC），其中6名使用双极刺激（Nucleus设备），6名使用单极刺激（Clarion设备）。使用固定电平的探测刺激和可变电平的掩蔽音，在中间电极的几个探测电平上测量fmSTC。使用双极刺激的受试者获得的平均fmSTC斜率（3.7 dB/mm）大约是使用单极刺激的受试者获得的平均斜率（1.2 dB/mm）的三倍。双极刺激受试者的平均空间带宽（2.6 mm）约为单极刺激受试者（4.6 mm）的一半。调谐曲线特征均未随探测电平发生显著变化。根据格林伍德[《美国声学学会杂志》33, 1344 - 1356 (1961)]的频率-位置方程，将以声频重新绘制的fmSTC与先前从正常听力和听力受损的声学聆听者获得的前掩蔽心理物理调谐曲线进行比较。电听觉中fmSTC的平均调谐特征类似于在高刺激水平下正常听力和听力受损的声学聆听者中观察到的宽调谐。这表明空间调谐不是限制许多人工耳蜗使用者言语感知的主要因素。
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