It is well known that intelligibility of speech reduces in the presence of ambient noise. However, studies show that all sounds are not affected uniformly (or equally) and that vowels are more robust to noise than consonants. In this study, intelligibility of various consonants is assessed and analyzed in stationary white noise and non-stationary babble noise conditions. Specifically, this study investigates the individual contribution of magnitude and phase spectra of a given speech signal on human speech recognition of consonants in noisy conditions. In this regard, three experiments are carried out. In experiment 1, clean signal, signal reconstructed with only magnitude spectrum information (magnitude only signal) and signal reconstructed with only phase spectrum information (phase only signal) are assessed for intelligibility. In experiment 2, noise is added to clean speech. From noisy speech, phase only signal and magnitude only signal are reconstructed and intelligibility tests are performed for all these three signals. In experiment 3, noise is added directly to the magnitude only and phase only signals reconstructed from clean speech and their intelligibility is assessed. Results of these experiments show that magnitude spectrum contributes more to intelligibility in clean condition than phase spectrum, while information from phase spectrum is more robust in noisy conditions. It is also observed that, among consonants, nasals are more susceptible to noise whereas fricatives and approximants were observed to be comparatively more robust.

翻译：众所周知，环境噪声会降低语音的清晰度。然而研究表明，并非所有语音成分都受到相同程度的影响，元音对噪声的耐受性比辅音更强。本研究评估并分析了不同辅音在稳态白噪声和非稳态背景噪声条件下的清晰度，重点探究给定语音信号中幅度谱与相位谱对人类辅音识别在噪声环境下的各自贡献。为此，我们开展了三项实验：实验1评估了纯净信号、仅利用幅度谱信息重建的信号（幅度仅存信号）和仅利用相位谱信息重建的信号（相位仅存信号）的清晰度；实验2在纯净语音中添加噪声，从带噪语音中重建相位仅存信号和幅度仅存信号，并对这三种信号进行清晰度测试；实验3将噪声直接添加至从纯净语音重建的幅度仅存信号和相位仅存信号中，评估其清晰度。实验结果表明，在无噪声条件下幅度谱对清晰度的贡献大于相位谱，而在噪声条件下相位谱的信息更为稳健。研究还发现，在辅音中鼻音对噪声更敏感，而摩擦音和近音表现出相对更强的噪声鲁棒性。