1. A method of concealing bit errors in a speech signal within a signal parameter quantizer including a processor, the method comprising: encoding a speech signal parameter based upon constraints placed on the signal parameter quantizer, the constraints being based upon naturally prohibitive speech parameter combinations in one or more speech parameter samples, the combinations including different types of parameters; comparing the encoded speech signal parameter against the constraints, wherein the comparison includes comparing a logarithmic gain value of the speech signal with a threshold function determined based on a difference between a plurality of logarithmic gain values of the speech signal; and modifying operation of the signal parameter quantizer when the constraints are violated.