Waisman Center, University of Wisconsin, 1500 Highland Avenue, Madison, Wisconsin 53705, USA.
J Acoust Soc Am. 2010 Feb;127(2):977-89. doi: 10.1121/1.3273897.
The possibility that "dead regions" or "spectral holes" can account for some differences in performance between bilateral cochlear implant (CI) users and normal-hearing listeners was explored. Using a 20-band noise-excited vocoder to simulate CI processing, this study examined effects of spectral holes on speech reception thresholds (SRTs) and spatial release from masking (SRM) in difficult listening conditions. Prior to processing, stimuli were convolved through head-related transfer-functions to provide listeners with free-field directional cues. Processed stimuli were presented over headphones under binaural or monaural (right ear) conditions. Using Greenwood's [(1990). J. Acoust. Soc. Am. 87, 2592-2605] frequency-position function and assuming a cochlear length of 35 mm, spectral holes were created for variable sizes (6 and 10 mm) and locations (base, middle, and apex). Results show that middle-frequency spectral holes were the most disruptive to SRTs, whereas high-frequency spectral holes were the most disruptive to SRM. Spectral holes generally reduced binaural advantages in difficult listening conditions. These results suggest the importance of measuring dead regions in CI users. It is possible that customized programming for bilateral CI processors based on knowledge about dead regions can enhance performance in adverse listening situations.
研究探索了“死区”或“光谱空洞”是否可以解释双侧人工耳蜗（CI）使用者和正常听力者之间某些性能差异的可能性。本研究使用 20 带噪声激励声码器模拟 CI 处理，研究了光谱空洞对在困难聆听条件下的言语接收阈值（SRT）和掩蔽释放比（SRM）的影响。在处理之前，通过头相关传递函数对刺激进行卷积，为听众提供自由场方向线索。在双耳或单耳（右耳）条件下通过耳机呈现处理后的刺激。使用 Greenwood 的 [（1990）。J. Acoust. Soc. Am. 87, 2592-2605] 频率位置函数，并假设耳蜗长度为 35mm，为可变大小（6 和 10mm）和位置（基底、中部和顶点）创建光谱空洞。结果表明，中频光谱空洞对 SRT 的干扰最大，而高频光谱空洞对 SRM 的干扰最大。光谱空洞通常会降低困难聆听条件下的双耳优势。这些结果表明测量 CI 用户的死区的重要性。根据关于死区的知识，为双侧 CI 处理器定制编程可能会增强在不利聆听情况下的性能。
