Comparing scalar and lattice based encoding of wavelet coefficients in sinusoidal plus wavelet packet coding

We have recently proposed a combined sinusoidal and Wavelet Packet Transform (WPT) codec for joint speech and audio coding. In this paper, we compare the performance of scalar and Z
_n
lattice based encoding of the WPT coefficients. The quantization of the WPT coefficients are determined by a psychoacoustic masking model, and it is identical in both cases. The audio quality remains the same for the scalar and the Z
_n
lattice based encoding, as only the encoding of the quantized WPT coefficients is changed. The mean bit rate of the coder (depending on the encoded signal) was reduced from 62-32 kbps to 54-30kbpsby applying the Z
_n
lattice based coding. Demonstration sound files are available at www-sc.enst-bretagne.fr/
^~
fek/demo/.