Summary: Audio watermarking consists in embedding inaudible information in a signal. This information is generally represented by a pseudorandom signal, the watermark, detected by means of a correlation measure. If robustness to malicious attacks is required, the pseudorandom signal must be secret and the detection is private. We present an approach that uses a cyclostationary signal as the watermark. While still privately detectable through correlation, the watermark may also be publicly detected by exploiting its property of cyclostationarity. The suitable choice of cyclostationary sequences provides for hiding both private and public data in the signal.