Patent ID: 8311812

Claim:
A method for extracting speech content from a digital speech signal, the speech content being characterized by at least one formant, each of the at least one formants characterized by an instantaneous frequency and an instantaneous bandwidth, the speech signal including a sequence of one or more of the at least one formants, the method comprising: extracting each one of the sequence of one or more of the at least one formants from the digital speech signal, said extracting further comprising: filtering the digital speech signal with a plurality of complex filters, the plurality of complex filters implemented in parallel as an overlapping processing chain, each of the complex filters having a bandwidth that overlaps with at least one other of the plurality of complex filters adjacent to it in the chain, each of the complex filters generating one of a plurality of complex filtered signals each including a real component and an imaginary component; generating an estimated instantaneous frequency and an estimated instantaneous bandwidth from each of the plurality of filtered signals using a product set formed of each of the plurality of filtered signals in combination with a single lag delay of each of the plurality of the filtered signals; and identifying each of the sequence of one or more formants of the digital speech signal as one of the at least one formants based on the estimated instantaneous frequencies and estimated instantaneous bandwidths; and reconstructing the speech content of the digital speech signal based on the identified sequence of formants using a speech processing system.