| 摘要 |
A method for embedding a data value in an audio signal comprises generating an echo of the audio signal, the echo polarity varying depending on the data value; associated data recovery methods, and apparatus means, are also independently claimed. First and second echoes, having respective first and second polarities, may be generated and combined with the audio signal; echoes may be generated by repeating audio signal portions. Data values may be represented by positive and negative (opposite) echoes having different delays. The polarity of gain factors applied to echoes may be inverted before echoes are combined with the audio signal. Echoes may be faded in and out to reduce obtrusiveness to the listener. The described data hiding can be used for watermarking, data communications, and audience surveying. The effects of natural echoes and/or periodicities in the audio signal can be removed by differencing measurements obtained at the different delays. |
