话音波形异常指数在话音质量客观评价中的应用

给出了一个话音串音的检测方案，提出了话音波形异常指数(Speech Wave Abnormal Index，SWAI)的概念和算法。SWAI描述了受到损害的话音浊音部分的准周期性被破坏的程度。它的提出有效地解决了串音检测问题，同时将其应用于话音质量客观实时评价，取得了理想的效果。     

New single-ended objective measure for non-intrusive speech quality evaluation

This article proposes a new output-based method for non-intrusive assessment of speech quality of voice communication systems and evaluates its performance. The method requires access to the processed (degraded) speech only, and is based on measuring perception-motivated objective auditory distances between the voiced parts of the output speech to appropriately matching references extracted from a pre-formulated codebook. The codebook is formed by optimally clustering a large number of parametric speech vectors extracted from a database of clean speech records. The auditory distances are then mapped into objective Mean Opinion listening quality scores. An efficient data-mining tool known as the self-organizing map (SOM) achieves the required clustering and mapping/reference matching processes. In order to obtain a perception-based, speaker-independent parametric representation of the speech, three domain transformation techniques have been investigated. The first technique is based on a perceptual linear prediction (PLP) model, the second utilises a bark spectrum (BS) analysis and the third utilises mel-frequency cepstrum coefficients (MFCC). Reported evaluation results show that the proposed method provides high correlation with subjective listening quality scores, yielding accuracy similar to that of the ITU-T P.563 while maintaining a relatively low computational complexity. Results also demonstrate that the method outperforms the PESQ in a number of distortion conditions, such as those of speech degraded by channel impairments.     

Effect of mobility on PRMA

PRMA, a packetized multiple access scheme for transmitting over short range radio channels, is a promising scheme to implement in a cellular system. PRMA requires little central control and allows hand-overs with minimal base station intervention. However, when mobile voice terminals move from one cell to another, they forfeit the slots reserved for them and, in addition, encounter hand-off delays leading to dropping of voice packets. The main problem is that a mobile terminal can lose more packets even after having secured a reservation. In this paper we use a path enumeration technique using signal flow graphs combined with equilibrium point analysis to analyze the effect of terminal mobility on the performance of PRMA in a cellular environment     

Capture effects on PRMA stability and performance

The effects of packet capture on packet reservation multiple access (PRMA) stability and capacity are obtained by Markov analysis. The results show that for strong capture, significantly improved performance is obtained     

GSM关于提升语音质量问题的探讨

GSM的语音质量是提升用户感知的关键指标之一。随着移动通信技术的快速发展,人们对传统业务即语音业务的要求越来越高。如何改善语音质量及提高移动网络的服务水平,已经成为移动运营商、设备制造商关注的焦点。文章针对影响语音质量的半速率、干扰、编码方式、覆盖等问题进行分析,提出了相关问题的处理思路和解决方法。     

客观视频质量评估方法研究

介绍了三类客观视频质量评估方法的基本概念和实现方法;在此基础上,提出了一种基于H.264视频压缩算法的无参考评估的特征提取方法,并进行了实验论证,证明该方法能够有效结合编码算法的特性进行无参考视频质量评估;最后对视频质量评估方法的研究进行了总结和展望。     

Subjective quality assessment for objective quality model development

It is examined whether expert subjects, typically avoided by subjective testing laboratories in favour of non-experts, provide more informative and appropriate SSCQE ratings for developing objective video quality models. The results show that, for training and testing objective video quality models, it is preferable to use data obtained from expert subjects than data obtained from non-expert subjects.     

PRMA协议发展及应用

介绍了PRMA协议及其发展,以及在无线多媒体信息传输中的应用.     

优先级与自适应PRMA协议的性能研究

本文对未来的第三代微蜂窝移动无线通信系统的多址访问协议进行了研究。研究了ＰＲＭＡ系统中同时存在高、低优先级话音终端的Ｐｐｒｍａ协议的性能。提出了话音终端具有自适应重发许可概率的Ａｐｒｍａ协议。利用系统仿真技术对协议的性能进行了估计。     

汉语言清晰度与客观指标U50的相关关系

为了使用客观指标评价与预测室内汉语言清晰度,通过室内汉语言清晰度主观评价实验,探讨了客观指标有益有害声能比U50与汉语言清晰度之间的相关关系,并得到两者之间的回归预测方程。研究表明汉语言清晰度SI与客观指标U50之间有着很强的相关关系,可以使用U50有效地评价汉语言清晰度。     

Improving speech quality of CELP coder

Although the speech quality of the code excited linear prediction (CELP) coder at 4800 bit/s is relatively good, it is still perceived as rough or noisy. The authors propose a residual shaping method that produces, without signal distortion, quality comparable to that obtained by adaptive postfiltering. The proposed method is particularly effective in the multiple tandeming environment.<>     

Pure delay effects on speech quality in telecommunications

The effect of transmission delay on speech quality in telecommunications is described, with human factors such as conversational mode and the talker's knowledge of the cause of delay taken into account. Objective quality estimation methods for delay effects are proposed, and these methods are applied in an actual communications network. In connection with delay perception in a telephone conversation, the assumption was verified that a talker expects a particular response time from a partner, and that delay that is outside this expectation time window is noticed. Taking this information into account, a subjective conversational experiment is controlled by six kinds of tasks by varying the temporal characteristics. Thus, a subjective assessment of delay effects is obtained by laboratory tests in relation to the detectability threshold, opinion rating, and conversational efficiency. Objective quality measures for each test were defined as a linear combination of temporal parameters that correspond closely to subjective qualities     

基于改进MFCC语音特征参数的语音质量评估的研究

.本文讨论了基于MFCC(Mel-Frequency Cepstral Coefficients)听觉感知模型的语音质量客观评估方法(EPESQ:Efficient Psychoacoustics Evaluation of Speech Quality)在网络语音质量客观评估中的应用,深入分析了EPESQ算法的基本原理,并对算法的MFCC语音特征参数进行了改进和性能分析.实验证明该算法在确保评测准确性的前提下,大大降低了算法的复杂度,具有较强的适应性,可靠性,实用性,完全可以应用于通信网络语音质量评估.     

Effects of speech coding on speaker verification

The impact of speech coding on automatic speaker verification is investigated. Two different coders, classifiers and parametric representations of speech are considered. It is found that coding degrades mean speaker verification accuracy. Classifications of speech frames, for a given speaker, fluctuate by up to 30% relative to the uncoded case     

The information index: An objective measure of speech transmission performance *

The maximal mutual information (channel capacity) between the input and output of a telephone connection was calculated, taking into account both the frequency and time domain aspects of this problem. This leads to define an « information index » which can be computed from objective measurements. Several examples are given, both for digital coders and for analogue transmission: they show that the information index has a very good correlation with the results of opinion tests. This index therefore constitutes the basis of a mathematical model for predicting the transmission performance of speech in a telephone network.     

基于稀疏表示的立体图像客观质量评价方法

提出了一种基于稀疏表示的立体图像质量评价方法 ,分为训练和测试两个部分。在训练部 分,通过训练不同频带的立体图像获得立体图像的稀疏字典;在测试部分,根据稀疏字典计 算得到立体图 像的稀疏特征,定义了稀疏特征相似度衡量原始和失真图像信息的差异,并根据稀疏字典计 算了频带增益和左右视点的融合权值,最后融合稀疏特征相似度作为立体图像质量的 客观评价值。在立体图像测试库上的实验结果表明,本文方法的评价结果与主观评价结果有 较好的相关性,符合人类视觉系统的感知。     

Prediction of stereoscopic video quality using objective quality models of 2-D video

The timely deployment of three-dimensional (3-D) video applications requires accurate objective quality measures, so that time consuming subjective tests can be avoided. Investigated is the correlation between subjective and objective evaluations of colour plus depth map 3-D video. Subjective tests are performed to determine the overall image quality and depth perception of a range of asymmetrically coded video sequences. The subjective results are used to determine more accurate objective quality assessment metrics for colour plus depth map based stereoscopic video.     

An objective measurement tool for MPEG video quality

A two-stage objective measurement model for MPEG-coded video is proposed. The first stage weights the coded video distortion according to the human visual system's response. It computes the frame-by-frame perceptual impairment in the decoded picture with respect to a reference picture; this includes low-pass spatial filtering, a Sobel operation to derive masking coefficients, and spatial masking on the raw error between reference and compressed pictures. The second stage, a cognitive emulator, provides a simulation of human high-level processing of visual information. This includes the very low temporal response of human viewers to image quality changes, and asymmetric behaviour in respect of picture quality changes from bad to good, and vice versa. With this model, we have been able to mimic quite accurately the temporally varying subjective picture quality of video sequences as recorded by the ITU-R SSCQE method.