Speech coding: Difference between revisions

Revision as of 23:57, 2 April 2005

Revision as of 07:34, 25 May 2005

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The two most important applications using speech coding are [[mobile phone]]s and [[internet phone]]s.

The techniques used in speech coding are similar to that in [[audio compression]] and [[audio coding]] where knowledge in [[psychoacoustics]] is used to transmit only data that is relevant to the human auditory system. For example, in narrow-band[[narrowband]] speech coding, only information in the frequency band 400Hz to 3500Hz is transmitted but the reconstructed signal is still adequate for intelligibility.

However, speech coding differs from audio coding in that there is a lot more statistical information available about the properties of speech. In addition, some auditory information which is relevant in audio coding can be unnecessary in the speech coding context. In speech coding, the most important criterion is always preservation of intelligibility of speech, with a constrained amount of transmitted data.