Antony W. Rix

Lucida Medical Ltd

A wireless receiver, in the form of a mobile telephone, includes a DAB receiver and a GSM/GPRS transceiver which enables bi-directional point-to-point data communications via a service provider. The DAB receiver is arranged to receive media data from an over-the-air broadcast channel, the media data primarily representing television and radio strea...

In the past few years, objective quality assessment models have become increasingly used for assessing or monitoring speech and audio quality. By measuring perceived quality on an easily-understood subjective scale, such as listening quality (excellent, good, fair, poor, bad), these methods provide a quick and repeatable way to estimate customer ex...

This paper reviews the development of perceptually-motivated models for quality assessment of speech transmission/storage systems. The aim is to predict a subjective mean opinion score (MOS) for non-linear, time-variant distortions such as lossy coders, channel errors or noise reduction, particularly for telecommunications applications. Because lin...

Perceptual models such as perceptual evaluation of speech quality (PESQ, ITU-T P.862) are now in common use for estimation of listening quality mean opinion score (MOS) of telephone networks and equipment. PESQ was originally designed for evaluation of narrowband telephony, with electrical and/or digital connections to the systems under test. The p...

As 3G video services mature, the ability to deliver adequate perceptual quality to end users will become increasingly important. The paper identifies the factors that influence perceptual quality and quantifies them using subjective testing. A new objective quality metric for measuring 3G video services is introduced. The metric is shown to predict...

This thesis discusses quality assessment of audio communications systems, in particular telephone networks. The goal is a model to estimate perceived quality, measured by subjective tests. Several authors have described perceptual models for this purpose, based on comparison of auditory transforms, which have been found to generalise better than si...

This paper discusses the relationship between subjective listening quality (LQ) mean opinion score (MOS), and objective quality score from the perceptual evaluation of speech quality (PESQ) model defined in ITU-T Recommendation P.862. The causes of variation of MOS between subjective tests, and the methods used in the ITU for comparing subjective a...

A new model for the perceptual evaluation of speech quality (PESQ) was recently standardized by the International Telecommunications Union as Recommendation P.862. Unlike previous codec assessment models, such as PSQM and MNB (ITU-T P.861), PESQ is able to predict subjective quality with good correlation in a very wide range of conditions, which ma...

A new model for the perceptual evaluation of speech quality (PESQ) was recently standardized by the International Telecommunications Union as Recommendation P.862. Unlike previous codec assessment models, such as PSQM and MNB (ITU-T P.861), PESQ is able to predict subjective quality with good correlation in a very wide range of conditions, which ma...

The speech quality delivered by a 3G network is determined by many factors, including speech and channel coding, the design of the device, and signal processing algorithms and their interactions. This paper examines the key speech quality issues in 3G networks, describes the basics of objective speech quality measurement, and highlights its applica...

Initial impressions of VoIP quality have not always been favourable. This paper discusses the issues behind delivering an 'appropriate' quality of service, specifically voice quality, by showing how design choices ultimately affect, and potentially limit, a customer's perception of VoIP quality. The paper continues by introducing new signal process...

Previous objective speech quality assessment models, such as bark spectral distortion (BSD), the perceptual speech quality measure (PSQM), and measuring normalizing blocks (MNB), have been found to be suitable for assessing only a limited range of distortions. A new model has therefore been developed for use across a wider range of network conditio...

Previous objective speech quality assessment models, such as bark spectral distortion (BSD), the perceptual speech quality measure (PSQM), and measuring normalizing blocks (MNB), have been found to be suitable for assessing only a limited range of distortions. A new model has therefore been developed for use across a wider range of network conditio...

This paper describes a new model for perceptual evaluation of speech quality (PESQ). This model is based on an integration of the perceptual speech quality measure (PSQM99) and the perceptual analysis measurement system (PAMS). PESQ is currently a draft ITU-T recommendation P.862, and is expected to replace P.861. PESQ provides a new international...

The perceptual analysis measurement system (PAMS) is an objective model designed to evaluate the perceived speech quality of telephone networks. Two key network properties, linear filtering and variable bulk delay, made previous models unsuitable for end-to-end measurement. This paper outlines the innovations that allow PAMS to take these propertie...

Assessment of perceived audio quality has become separately established for telephone-bandwidth and high-quality audio. Seeking a model for use across both applications, we examine requirements for end-to-end speech quality assessment of channels at a range of audio bandwidths, in the presence of coding and noise. Results from a new wideband versio...

End-to-end audio quality measurement of non-linear communication networks requires existing codec assessment models to be extended. Variable delay in voice over IP systems and linear filtering in analogue interfaces are shown to cause problems. Results suggest that a perceptual analysis/measurement system (PAMS) can take account of these effects an...

Perceptual quality assessment models were initially developed to predict subjective quality of codecs. Experience with telephony applications has found that today's complex networks make assessment difficult. Analogue interfaces and variable delay are amongst the technologies used in current voice transmission systems-and often make the first gener...

First Page of the Article

As communications systems have increased in complexity it has become increasingly difficult to measure their performance objectively. In particular, when signals are compressed for more efficient transmission, conventional engineering metrics fail to predict the performance experienced by the end user — the customer. A new generation of objective m...

Performance factors such as quality are important in a competitive telecommunications market where price differentials have been minimised. An important aspect of service performance is speech quality. Efficient network design and service delivery is facilitated by objective assessment of performance as perceived by customers. Such assessment is no...

A new model for perceptual evaluation of speech quality (PESQ) was recently standardised by the ITU-T as recommendation P.862. Unlike previous codec assessment models, such as PSQM and MNB (ITU-T P.861), PESQ is able to predict subjective quality with good correlation in a very wide range of conditions, that may include coding distortions, errors,...