Patent ID: 8364494

Claim:
An apparatus comprising: a first speech encoder configured to encode a lowband speech signal into at least an encoded lowband excitation signal; a second speech encoder configured to generate a highband excitation signal based on the encoded lowband excitation signal and to encode a highband speech signal into a stream of highband coding parameters; and a filter bank having (A) a lowband processing path configured to receive a wideband speech signal having frequency content between at least 1000 and 6000 Hz and to produce the lowband speech signal and (B) a highband processing path configured to receive the wideband speech signal and to produce the highband speech signal, wherein the lowband speech signal is based on a first portion of the frequency content of the wideband signal, the first portion including the portion of the wideband signal from 1000 to 2000 Hz, and wherein the highband speech signal is based on a second portion of the frequency content of the wideband signal, the second portion including the portion of the wideband signal from 5000 to 6000 Hz, and wherein each of the lowband speech signal and the highband speech signal is based on a third portion of the frequency content of the wideband signal, the third portion including a portion of the wideband signal between 2000 and 5000 Hz that has a width of at least 400 Hz, and wherein a frequency response of each of the lowband processing path and the highband processing path over the third portion is not less than minus twenty decibels (−20 dB), and wherein the stream of highband coding parameters includes a plurality of gain factors that is based on the highband excitation signal, and wherein a sum of a sampling rate of the lowband speech signal and a sampling rate of the highband speech signal is less than a sampling rate of the wideband signal, and wherein at least one among said first speech encoder, said second speech encoder, and said filter bank includes a processor.