Patent ID: 6885986

Claim:
A method of determining successive pitch periods/frequencies in an audio equivalent signal; the method comprising: dividing the audio equivalent signal into a sequence of mutually overlapping or adjacent pitch detection segments; determining an initial value of the pitch frequency/period for each of the pitch detection segments; and based on the determined initial value, determining a refined value of the pitch frequency/period; characterised in that the step of determining a refined value of the pitch frequency/period comprises: forming a sequence of pitch refinement segments by: positioning a chain of time windows with respect to the audio equivalent signal; and weighting the signal according to an associated window function of the respective time window; each pitch refinement segment being associated with at least one of the pitch detection segments forming a filtered signal by filtering each pitch refinement segment to extract a frequency component with a frequency substantially corresponding to an initially determined pitch frequency of an associated pitch detection segment; and determining the successive pitch periods/frequencies from the filtered signal.