Increased watermark-to-host correlation of uniform random phase watermarks in audio signals

We analyze the watermark-to-host correlation (WHC) of random phase watermarks, in the context of additive embedding and blind correlation-detection of the watermark in audio signals. Interestingly, we find that WHC is higher when a legitimate watermark is present in the audio signal. Instead of trying to minimize the WHC, one could also attempt to harness this increased correlation in order to result in better detection performance. The analysis shows that uniformly distributed phase difference (between the host signal and the watermark) provides maximum advantage. It is also verified that, a uniformly distributed watermark phase provides the most advantage, experimented over a variety of audio signals.