Speech coding is the process of digitizing the voice
in a few bits as possible. Parametric Coding is the
encoding technique at which the parameters of the
speech signal will be extracted frame by frame
during the encoding process. Code Excited Linear
Prediction “CELP” is one major type of that
category of CODECs. The comparison between the
CODECs is based upon the band width, the speech
quality and the associated CODEC delay. It has
been proven that the quality is inversely
proportional to the compression ratio. But what
will happen if the speech is compressed more and
at the same time the spoken language changed?
This paper is made to answer about this question.
In this paper an extensive testing is done on ITU
G.723.1 (5.3 kbps) and 3GPP Adaptive Multi Rate
“AMR” (12.2 kbps). The test is made using 3
groups of speech samples (English, Arabic and
Cairo accent) with different speakers’ gender. The
evaluation method used is the ITU PESQ
algorithm. It has been proved that the speech
quality dramatically decreases as the compression
ratio increases, which will be rather lower and
unstable for Arabic and Cairo accent over that of
the English language. |
