Patent ID: 7236927
Filing Date: 2007-06-26
Classification: G10L

Abstract:
1. A method of searching for an interpolated peak of a Normalized Correlation Square (NCS) signal derived from an audio signal, the NCS signal being represented as a first ratio of a correlation square signal c 2 (k) to an energy signal E(k), where k represents time lags spanning a range of integer k-values, the interpolated peak being near a known local peak c 2 (k p )/E(k p ) of the NCS signal, comprising: (a) producing quadratically interpolated correlation (QIC) signal values (ci) at interpolated time lags between time lag k (b) squaring each of the QIC signal values to produce square QIC signal values (ci (c) producing an individual interpolated energy signal value (ei) corresponding to each of the square QIC signal values, wherein second ratios of the square QIC signal values (ci (d) selecting, as the interpolated peak, a largest interpolated NCS signal value among the interpolated NCS signal values without evaluating the second ratios.