Patent ID: 8463604

Claim:
A method of encoding speech, comprising: receiving an input signal representing a property of speech; quantizing the input signal, thus generating a quantized output signal; prior to said quantization, supplying a version of the input signal to a first noise shaping filter having a first set of filter coefficients, thus generating a first filtered signal based on that version of the input signal and the first set of filter coefficients; following said quantization, supplying a version of the quantized output signal to a second noise shaping filter having a second set of filter coefficients different than said first set, thus generating a second filtered signal based on that version of the quantized output signal and the second set of filter coefficients; performing a noise shaping operation to control a frequency spectrum of a noise effect in the quantized output signal caused by said quantization, wherein the noise shaping operation is performed based on both the first and second filtered signals; and transmitting the quantized output signal in an encoded signal, the quantized output signal based, at least in part, on the first filtered signal and the second filtered signal.