16. The method of claim 9 , wherein each candidate codevector is a sub-codevector of a composite codevector.
9. A method of quantizing a vector representative of a portion of a speech or audio signal in an encoder, comprising: (a) determining legal candidate codevectors among a set of candidate codevectors based upon one or more illegal space definitions, the candidate codevectors including line spectral frequencies (LSFs), wherein the one or more illegal space definitions define invalid spacing characteristics of LSFs; (b) deriving a separate error term corresponding to each legal candidate codevector, each error term being a function of the vector and the corresponding legal candidate codevector; (c) determining a best legal candidate codevector among the legal candidate codevectors based on the error terms, whereby the best legal candidate codevector corresponds to a quantization of the vector; and (d) transmitting to a decoder a signal representative of the portion of the speech or audio signal based on the best legal candidate codevector.