Waisman Center, University of Wisconsin, Madison, WI 53705, USA.
J Acoust Soc Am. 2009 Nov;126(5):2522-35. doi: 10.1121/1.3238242.
A cochlear implant vocoder was used to evaluate relative contributions of spectral and binaural temporal fine-structure cues to speech intelligibility. In Study I, stimuli were vocoded, and then convolved through head related transfer functions (HRTFs) to remove speech temporal fine structure but preserve the binaural temporal fine-structure cues. In Study II, the order of processing was reversed to remove both speech and binaural temporal fine-structure cues. Speech reception thresholds (SRTs) were measured adaptively in quiet, and with interfering speech, for unprocessed and vocoded speech (16, 8, and 4 frequency bands), under binaural or monaural (right-ear) conditions. Under binaural conditions, as the number of bands decreased, SRTs increased. With decreasing number of frequency bands, greater benefit from spatial separation of target and interferer was observed, especially in the 8-band condition. The present results demonstrate a strong role of the binaural cues in spectrally degraded speech, when the target and interfering speech are more likely to be confused. The nearly normal binaural benefits under present simulation conditions and the lack of order of processing effect further suggest that preservation of binaural cues is likely to improve performance in bilaterally implanted recipients.
耳蜗植入体声码器用于评估频谱和双耳时间精细结构线索对语音可懂度的相对贡献。在研究 I 中，刺激被声码化，然后通过头部相关传递函数 (HRTF) 卷积，以去除语音时间精细结构，但保留双耳时间精细结构线索。在研究 II 中，处理顺序被颠倒，以去除语音和双耳时间精细结构线索。在安静环境中和存在干扰语音的情况下，以双耳或单耳（右耳）条件下，对未处理和声码化语音（16、8 和 4 个频带）进行自适应测量语音接收阈值 (SRT)。在双耳条件下，随着频带数的减少，SRT 增加。随着频带数的减少，观察到目标和干扰语音之间空间分离的更大益处，尤其是在 8 频带条件下。这些结果表明，在目标和干扰语音更有可能混淆的情况下，双耳线索在频谱退化语音中起着重要作用。在当前的模拟条件下，双耳受益几乎正常，并且不存在处理顺序效应，这进一步表明，保留双耳线索可能会提高双侧植入接受者的性能。
