93. The encoder of claim 92 , further comprising: sixth means for generating an error term corresponding to each legal candidate codevector, each error term being a function of the vector and the corresponding legal candidate codevector, wherein the fourth means includes means for determining the best legal candidate codevector based on the error terms.
92. An encoder for quantizing a vector representative of a portion of a speech or audio signal, comprising: first means for generating a set of candidate codevectors that include line spectral frequencies (LSFs); second means for storing an illegal space definition representing illegal vectors, wherein the illegal space definition defines invalid spacing characteristics of LSFs; third means for determining legal candidate codevectors among the set of candidate codevectors using the illegal space definition; fourth means for determining a best legal candidate codevector among the one or more legal candidate codevectors, whereby the best legal candidate codevector corresponds to a quantization of the vector; and fifth means for transmitting to a decoder a signal representative of the portion of the speech or audio signal based on the best legal candidate codevector.