Computational effectiveness enhancement of frequency domain pitch estimators

Apparatus for estimating a pitch frequency of a speech signal, comprising:

• means for determining a line spectrum of a frame of a speech signal, the spectrum comprising a plurality of spectral lines having respective line amplitudes and line frequencies;
• means for selecting a predefined number of said spectral lines having the highest amplitudes among said spectral lines, wherein the number of selected spectral lines is less then the total number of said plurality of spectral lines;
• means for calculating a preliminary utility function over a pitch frequency range, thereby providing a preliminary utility function value for each pitch frequency in said range that is a measure of a compatibility of said selected spectral lines with said pitch frequency;
• means for identifying a predefined number of preliminary pitch frequency candidates at least partly responsive to said preliminary utility function, wherein each preliminary pitch frequency candidate is a local maximum of said preliminary utility function;
• means for calculating a final utility score for each of said preliminary pitch frequency candidates;
• and
• means for selecting any of said plurality of preliminary pitch frequency candidates to be an estimated pitch frequency of said speech signal at least partly responsive to any of said final utility scores.

A computer program embodied on a computer-readable medium, the computer program comprising:

• a first code segment operative to determine a line spectrum of a frame of a speech signal, the spectrum comprising a plurality of spectral lines having respective line amplitudes and line frequencies;
• a second code segment operative to select a predefined number of said spectral lines having the highest amplitudes among said spectral lines, wherein the number of selected spectral lines is less then the total number of said plurality of spectral lines;
• a third code segment operative to calculate a preliminary utility function over a pitch frequency range, thereby providing a preliminary utility function value for each pitch frequency in said range that is a measure of a compatibility of said selected spectral lines with said pitch frequency;
• a fourth code segment operative to identify a predefined number of preliminary pitch frequency candidates at least partly responsive to said preliminary utility function, wherein each preliminary pitch frequency candidate is a local maximum of said preliminary utility function;
• a fifth code segment operative to calculate a final utility score for each of said preliminary pitch frequency candidates;
• and
• a sixth code segment operative to select any of said plurality of preliminary pitch frequency candidates to be an estimated pitch frequency of said speech signal at least partly responsive to any of said final utility scores.