Appeal No. 2003-1053
Application No. 09/306,960
Appellant's invention relates to refinement of pitch detection. An understanding
of the invention can be derived from a reading of exemplary claim 1, which is
reproduced below.
1. 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;
characterized 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.
2
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