1. An audio watermark detection system, comprising: a pattern generator to generate a watermark (w) comprised of two defined values (a and b); and a correlation module to detect whether the watermark is present in a watermarked audio signal (y), wherein the correlation module computes a normalized correlation value from the watermarked audio signal and from the watermark based upon: a difference between the sum of signal samples of y for which the corresponding watermark bit w matches a divided by the cardinality of watermark samples matching a, and the sum of signal samples of y for which the corresponding watermark bit w matches b divided by the cardinality watermark samples equal to b.