【作者】 杨波；

【导师】 傅汝林；

【作者基本信息】 成都理工大学 ， 信号与信息处理， 2003， 硕士

【摘要】 语音信号是进行通信所主要使用的一种手段。目前语音通信系统飞速发展，相应地评价这些系统的语音质量一直备受人们的关注。语音质量评价大体上分为两类：主观评价和客观评价。建立在谱失真测度基础上的客观音质评价是当前研究的活跃课题。在前人研究的基础上，本文着重研究对巴克谱失真(Bark Spectral Distortion)测度的改进以及它们在语音客观评价方面的应用。 论文利用人耳的听觉掩蔽特性对BSD测度进行了改进研究，以提高主客观音质评价的相关度。研究主要集中在应用掩蔽效应的两方面： 1．传统的BSD测度未考虑影响人耳感知判断的帧间掩蔽特性。MBSD测度利用听觉瞬时掩蔽效应，在失真距离的计算中，只包含听觉能够感知的失真。MBSD失真距离定为响度差的平均。初步的实验结果表明，这种改进的测度性能优于原BSD测度。 2．心理声学的研究表明，人对声音的掩蔽现象不仅有瞬时掩蔽，而且还有同时性掩蔽。论文的第二部分研究了利用同时掩蔽的EBSD测度。该测度充分地反映人耳听觉系统的感知特性，且计算简便。针对特定的语音条件，EBSD测度的评价结果与主观评价的相关度达到了0.95左右。研究中对噪声掩蔽门限进行尺度伸缩，得到的相关结果较其他测度，不仅具有较好的普适性，而且主客观评价结果之间具有更高的相关系数。 可以推断这些测度作为对语音系统进行的客观音质评价，会具有好的有效性和实用性。深入研究利用听觉感知特性的客观失真测度，及其在客观音质评价中的应用，不仅在军事上具有现实意义，而且在语音增强、语音识别等领域的特征提取的研究中也会得到广泛应用。更多还原

【Abstract】 Speech signal is an important means in communication. Currently as voice communication systems have been rapidly change, there is increasing interest in the development of a speech quality assessment. There are two ways include subjective and objective speech quality of assessment in principle. The most widely-used objective speech quality measure demonstrate the performance of speech codecs is the in-output-based objective measure of speech quality, based on the measure of spectral distortion. This dissertation focuses on the researches of modified Bark spectral distortion measure with the auditory masking properties, as well as their application to objective assessments of speech quality. The major contributions of this dissertation are as follows:1.The BSD measure is based on a perceptual model that incorporates the frequency smearing within a given short-time frame, but not taken into account the inter-frame masking effects that impact human perceptual discrimination. Hence an opportunity exists to incorporate these inter-frame temporal masking effects into the BSD measure to improve its performance. Is computed only from perceptual distortion of the speech in the MBSD measure, imperceptible distance contributions are ignored. The MBSD defines the distortion as the average difference of estimated loudness. Preliminary experimental results show that the MBSD measure is a preferable speech quality assessment that can consist with subjective assessment of speech quality well and the correlative coefficient of MBSD over the conventional BSD.2.A psychoacoustic experiment shows that human hearing masking effects is not only temporal masking, is but also including simultaneous masking. Another part of this dissertation studies the EBSD measure with simultaneous masking. It can embody adequately the perception properties of the human auditory system with simple computing. It is found in experimentalinvestigation that the correlative coefficient of the MOS predicted by EBSD and the subjective MOS measure can reach up to about 0.95. Noise masking threshold plays an important role in estimating perceptual distortion in the EBSD. The performance of the EBSD measure has been examined for speech data with coding distortions by varying the scaling factor. Compared with the MBSD, The performance of the EBSD measure is slightly better than that of the MBSD.We can conclude that these measures have certain validity and utility to appraise the quality of speech systems. Objective distortion measure with perceptual properties is studied deep, which has been applied to speech quality assessment successfully. Not only in militarily, but also is widely applied to research of feature extraction in speech enhancement and speech recognition.更多还原