Subjective evaluation of high quality audio noises

Authors

  • T. Grusec Commun. Res. Centre, Ottawa, Ont., Canada

Keywords:

audio acoustics, audio systems, codecs, bit-rate reduction, audio codecs, digital audio bit-rate, psychoacoustic models, post-processing, fine-grained comparisons, high quality audio devices

Abstract

Radio-frequency spectrum restrictions in radio broadcasting, and space limitations in other applications (such as audio storage on high cost media) demand bit-rate reduction. At the Communications Research Centre, we have been evaluating the subjective quality of audio codecs that reduce digital audio bit-rate by factors of 4 or more, depending on the application. The algorithms used to achieve such reductions are based on psychoacoustic models of hearing so that, theoretically, codecs should be able to operate transparently. With the best of these codecs, operating at their higher bit-rates, such transparency is likely to be true for average listeners. However, very subtle differences among these codecs can become magnified, for example, by operating several of these codecs in tandem, or by post-processing applied after bit-rate reduction (typical in broadcasting). Differences among the codecs may, thus, become more obvious at the end of complex broadcast chains. Thus, the codecs are not necessarily fully equivalent, and it is essential to make fine-grained comparisons before choosing among them for broadcast, and other critical applications. For achieving such comparisons, we use special conditions and procedures. We believe these special features are adaptable for the subjective evaluation of any high quality audio devices

Published

1994-09-01

How to Cite

1.
Grusec T. Subjective evaluation of high quality audio noises. Canadian Acoustics [Internet]. 1994Sep.1 [cited 2021Apr.17];22(3):57-8. Available from: https://jcaa.caa-aca.ca/index.php/jcaa/article/view/848

Issue

Section

Proceedings of the Acoustics Week in Canada