Key points are not available for this paper at this time.
Vector quantizers of one and two bits per sample are designed for a training sequence of 640000 speech samples and tested on a speaker not in the training sequence. Both full search vector quantizers and tree search vector quantizers are considered. The tree searched codes are suboptimal in an information theory sense, but they have a greatly reduced search effort and provide a vector successive approximation quantizer.
Gray et al. (Thu,) studied this question.