Uses of peaks in audio auto-correlation Do you know of any algorithms for audio processing that make use of peaks in auto-correlation function? I am currently involved in research on mapping methodology for dynamic algorithms. I came recently over an algorithm for detection of fundamental frequency in audio signals, which has a dynamic structure I am looking for - the execution time of the algorithm varies with the number of peaks in the signal's auto-correlation:

while (i &lt; hsize)

    // Search for peaks in auto-correlation:
    if((r[i] &gt; 0) &amp;&amp; (r[i]&gt;r[i-1]) &amp;&amp; (r[i]&gt;=r[i+1])){

            temp = 0.25f*(r[i+1]-r[i-1]);
            temp = r[i] - temp*temp/(0.5f*(r[i+1]+r[i-1]) - r[i]);
            n = n1[i] + n2[i];
            if ((rmax*n) &lt; (temp*nmax)) {imax=i; rmax=temp; nmax=n;}.

            i++;}
    else{i++;}


This would be perfect as a studying example for my methodology, but the problem is that there is only a couple of lines inside the loop, so the overhead of adding my techniques becomes too big for the problem of this size. Now I am wondering if there exist any similar algorithms in audio processing, i.e. also making use of peaks in auto-correlation function but perform more extensive calculations for each peak?
The YIN Algorithm could be of interest to you. It's based on autocorrelation and is used for estimating the fundamental frequency.

A. de Cheveigné, H. Kawahara: YIN, a fundamental frequency estimator for speech and music, Proceedings of ICMC 2005. Download PDF.

A C++ implementation is also available.