Won Jong Ho, Schimmel Steven M, Drennan Ward R, Souza Pamela E, Atlas Les, Rubinstein Jay T
VM Bloedel Hearing Research Center, University of Washington, Box 357923, Seattle, WA 98195-7923, United States.
Hear Res. 2008 May;239(1-2):1-11. doi: 10.1016/j.heares.2008.01.009. Epub 2008 Jan 26.
This study evaluated the maximal attainable performance of speech enhancement strategies based on coherent modulation filtering. An optimal adaptive coherent modulation filtering algorithm was designed to enhance known signals from a target talker in two-talker babble noise. The algorithm was evaluated in a closed-set, speech-recognition-in-noise task. The speech reception threshold (SRT) was measured using a one-down, one-up adaptive procedure. Five hearing-impaired subjects and five cochlear implant users were tested in three processing conditions: (1) original sounds; (2) fixed coherent modulation filtered sounds; and (3) optimal coherent modulation filtered sounds. Six normal-hearing subjects were tested with a 6-channel cochlear implant simulation of sounds processed in the same three conditions. Significant improvements in SRTs were observed when the signal was processed with the optimal coherent modulation filtering algorithm. There was no benefit when the signal was processed with the fixed modulation filter. The current study suggested that coherent modulation filtering might be a promising method for front-end processing in hearing aids and cochlear implants. An approach such as hidden Markov models could be used to generalize the optimal coherent modulation filtering algorithm to unknown utterances and to extend it to open-set speech.
本研究评估了基于相干调制滤波的语音增强策略的最大可实现性能。设计了一种最优自适应相干调制滤波算法，以在双说话者嘈杂噪声中增强来自目标说话者的已知信号。该算法在封闭集噪声中的语音识别任务中进行了评估。使用一降一升自适应程序测量语音接收阈值（SRT）。五名听力受损受试者和五名人工耳蜗使用者在三种处理条件下进行了测试：（1）原始声音；（2）固定相干调制滤波声音；（3）最优相干调制滤波声音。六名听力正常的受试者使用在相同三种条件下处理的声音的6通道人工耳蜗模拟进行了测试。当使用最优相干调制滤波算法处理信号时，观察到SRT有显著改善。当使用固定调制滤波器处理信号时没有益处。当前研究表明，相干调制滤波可能是助听器和人工耳蜗前端处理的一种有前途的方法。诸如隐马尔可夫模型之类的方法可用于将最优相干调制滤波算法推广到未知话语，并将其扩展到开放集语音。
