Acoustic correlates of phonetic perception

描述(申请人提供)：如果我们对语音识别背后的听觉和知觉机制有更深入的了解，许多实际和理论问题都可以得到解决。这种知识的实际应用包括改进人工耳蜗信号处理器，改进语音合成设备，开发健壮的语音识别算法，以及为听力受损的说话者开发训练设备。拟议中的实验分为三大类。我们设计了一系列广泛的实验来检验在上一次资助期间开发的一个新的元音感知模型的有效性。该模型假设元音识别是通过模板匹配过程来识别的，模板匹配过程涉及将窄带输入频谱与一组平滑的频谱形状模板进行比较，这些模板是通过正常的语音暴露学习的。在前一次赠款期间进行的评估表明，该模型能够识别来自大型多人数据库的元音，准确率接近人类听者的准确率。我们希望将这项工作扩展到以下问题：(1)对元音识别的时间和光谱线索的整合进行建模；(2)测试该理论对语音环境、信号周期和共振峰幅度关系等频谱形状特征等因素变化的稳健性；以及(3)纳入一种心理上看似合理的归一化方案，该方案可能解释听者识别具有不同声道特征的说话者的语音的能力。将进行第二组实验，测量语音信号向听者传递了多少语音信息，这些语音信号是由专门设计的语音合成算法生成的，这些算法只保留了原始语音信号的一些特征，而故意删除或扭曲了其他提示。这些结果将使我们能够对调节语音识别的潜在光谱表征的性质做出推断。第三项工作旨在评估在上一次赠款期间开发的一种新的听觉频率分析理论。该理论假设听觉频谱不是在外周计算的，而是通过分析听神经的放电模式在中枢神经系统计算的。将开发一个软件模拟，用于测试该理论的有效性。

DESCRIPTION (provided by applicant): Numerous practical and theoretical problems could be addressed if we had a deeper understanding of the auditory and perceptual mechanisms underlying phonetic recognition. Practical applications of this knowledge include improvements to cochlear implant signal processors, the improvement of speech synthesis devices, the development of robust speech recognition algorithms, and the development of training devices for hearing-impaired speakers. The proposed experiments fall into three major categories. An extensive series of experiments is designed to test the validity of a new model of vowel perception that was developed during the previous grant period. The model assumes that vowel identity is recognized by a template-matching process involving the comparison of narrow band input spectra with a set of smoothed spectral-shape templates that are learned through ordinary exposure to speech. An evaluation conducted during the previous grant period showed that the model is capable of recognizing vowels from a large, multitalker database with accuracy approaching that of human listeners. We would like to extend this line of work to address issues such as: (1) modeling the integration of temporal and spectral cues to vowel identity, (2) testing the robustness of the theory to variation in factors such as phonetic environment, signal periodicity, and spectral shape features such as formant amplitude relations, and (3) incorporation of a psychologically plausible normalization scheme that might account for the ability of listeners to recognize speech from talkers with diverse vocal-tract characteristics. A second set of experiments will be run which measure how much phonetic information is transmitted to listeners by speech signals that have been generated by specially designed speech synthesis algorithms that preserve only some characteristics of the original speech signal, while purposely removing or distorting other cues. The results will allow inferences to be drawn about the nature of the underlying spectral representations that mediate phonetic recognition. A third line of work is designed to evaluate a new theory of auditory frequency analysis that was developed during the previous grant period. The theory assumes that the auditory spectrum is calculated not at the periphery but in the central nervous system through an analysis of auditory nerve firing patterns. A software simulation will be developed for use in testing the validity of the theory.