  This paper is concerned with scalar quantization of transform coefficients in
an audio codec. The generalized Gaussian distribution (GGD) is used as an
approximation of one-dimensional probability density function for transform
coefficients obtained by modulated lapped transform (MLT) or modified cosine
transform (MDCT) filterbank. The rationale of the model is provided in
comparison with theoretically achievable rate-distortion function. The
rate-distortion function computed for the random sequence obtained from a real
sequence of samples from a large database is compared with that computed for
random sequence obtained by a GGD random generator. A simple algorithm of
constructing the Extended Zero Zone (EZZ) quantizer is proposed. Simulation
results show that the EZZ quantizer yields a negligible loss in terms of coding
efficiency compared to optimal scalar quantizers. Furthermore, we describe an
adaptive version of the EZZ quantizer which works efficiently with low bitrate
requirements for transmitting side information
