Log-scaling watermark detection in digital audio watermarking

A pitch-scaling modification of a watermaked signal is a severe attack on audio watermarking techniques. In particular, watermarking techniques using a pseudonoise (PN) sequence as a secret key are fragile in the face of this modification because of the desynchronization between the original and embedded PN sequences. We, therefore, propose a log-scaling watermark detection method in this paper to cope with this problem. This method is based on a general logarithm operation in the frequency or quef'rency axis in the decoding process. This method is also advantageous in that no other modification of the original embedding process is necessary. The validity of the log-scaling watermark detection method herein proposed is evaluated by employing the time-spread echo method as an example of such a watermarking technique.