The adequate evaluation of sound quality is an important issue for the lossy compression codecs, such as MP3. ITU-R Rec BS. 1387-1 (PEAQ – Perceptual Evaluation of Audio Quality) is the most widely used method to evaluate sound quality objectively. However, PEAQ can only be used for mono signals or two channel stereo signals, because it considers only timbral factors when assessing sound quality. This paper introduces an improved objective quality assessment method that can be used for mono signals and multichannel audio signals that considers both “spatial” and “timbral” factors. The “spatial” factors, which measure perceptual distortions in spatial impression, are important to evaluate the quality of multichannel sounds.

This paper presents a design of an MPEG-2 layer 2 audio decoder that decodes signals of 5 channels (left, right, center, left surround, and right surround). It is backwards compatible with MPEG-1 decoder and its left/right channel coding supports stereo, dual channel, and single channel modes. The joint stereo mode supports four extension modes including Dolby Prologic decoding. Besides, the proposed system supports channel switching, dynamic crosstalk, and phantom coding modes to recover multichannel signal, and supports most options described in ISO/IEC 13818-3. The system has been implemented using FPGAs (Field Programmable Gate Array) which is easily mappable in ASIC, and proved to work as an excellent MPEG-2 multichannel audio decoder.