Influence of Languages on Celp Codecs Performance

Joint Enhancement and Coding of Speech by Incorporating Wiener Filtering in a CELP Codec

The performance of speech communication applications in the field of mobile devices is often hampered by background noises and distortions. Therefore, noise attenuation methods are commonly used as a pre-processing method, cascaded with the speech-codec. We demonstrate that the performance of such combinations of speech enhancement and coding methods can be improved by joining the two methods i...

Distributed Speech Recognition with Codec Parameters

Communication devices which perform distributed speech rec-ognition (DSR) tasks currently transmit standardized coded parameters of speech signals. Recognition features are extracted from signals reconstructed using these on a remote server. Since reconstruction losses degrade recognition performance, propos-als are being considered to standardize DSR-codecs which derive recognition features, t...

A Range of Low and High Delay CELP Speech Codecs between 8 and 4 kbits/s

In this paper we study the performance and the error sensitivities of six CELP [I] based codecs operating between 8 and 4 kbitsls. Codecs using both forward and backward adaption of the linear prediction coefficients and the long term predictor (LTP) are described. Initially we describe four low delay codecs which all use backward adaption of the LPC coefficients but which differ in their use o...

Zero-redundancy error protection for CELP speech codecs

Improved Noise Weighting in CELP Coding of Speech - Applying the Vorbis Psychoacoustic Model To Speex

One key aspect of the CELP algorithm is that it shapes the coding noise using a simple, yet effective, weighting filter. In this paper, we improve the noise shaping of CELP using a more modern psychoacoustic model. This has the significant advantage of improving the quality of an existing codec without the need to change the bit-stream. More specifically, we improve the Speex CELP codec by usin...