A new detection method for tampered audio signals based on discrete cosine transformation

Abstract

This article proposes a detection method to solve the problem of determining whether the audio data has been tampered with or not In many situations, we need to authenticate audio data as an original or some tampered version. For example, we have to verify the owner of audio data once the right is debated. By using the proposed method, we can easily authenticate whether the audio data had been altered or not and thus make the said data are more reliable. In the scheme, the audio signals are transformed by DCT, the DC and low-frequency AC are hidden in the medium-frequency AC. With the inverse transformation of DCT, we can obtain the protected audio data. To authenticate the audio signals, the protected data are transformed by DCT: then the system extracts the embedded DC and low-frequency AC from the medium-frequency AC. After the inverse DCT, we can extract the audio data and compare with the protected data. The extracted audio data will greatly differ from the protected data if these data are altered; without tampering, the two are quite similar. Also, if the protected audio data are distorted by MP3 compression, the previous situation still holds.