Second European Conference on Speech Communication and Technology

Genova, Italy
September 24-26, 1991


Evaluation and Improvement of Coded Speech Quality Degraded by Cell Loss in ATM Networks

Hiromi Nagabuchi, Nobuhiko Kitawaki

NTT Telecommunication Networks Laboratories, Musashino-shi, Tokyo, Japan

This paper investigates the subjective effects of speech quality impairments resulting from cell loss and coding distortion, which are likely to occur in communications systems using ATM (Asynchronous Transfer Mode). A method is proposed for improving speech quality degraded by cell loss. This method uses an LPC (Linear Predictive Coding) spectrum-shaping filter. The performance of the proposed method is compared with that of a speech signal waveform substitution method. Listening tests were used to assess both quality (defined using a rating scale) and intelligibility. Speech quality evaluation results are presented for various speech coding methods, methods for dividing speech signals into cells, unit cell sizes, and missing-cell-rates. Experimental results show the robustness of embedded coding against cell loss and the effectiveness of the proposed quality-improvement method. Keywords: Speech quality evaluation; ATM; Cell loss

Full Paper

Bibliographic reference.  Nagabuchi, Hiromi / Kitawaki, Nobuhiko (1991): "Evaluation and improvement of coded speech quality degraded by cell loss in ATM networks", In EUROSPEECH-1991, 603-606.