Improvement of Embedding Capacity and Quality of DWT-Based Audio Steganography Systems

Steganography is a method for hiding information in a host signal. The host signal can be a still image, speech or video and the message signal that is hidden in the host signal can be a text, image or an audio signal. In this paper, a steganography method is proposed in which information hiding in the least significant bits (LSBs) of wavelet coefficients and also direct message replacement in wavelet subbands are performed. In this method, the host signal is segregated into several subbands through discrete wavelet transform (DWT). Then, the given subbands are compared with hearing threshold and the subbands which have lower or equal energy compared to the mentioned hearing threshold are utilized for steganography. To retrieve steganography information, inverse wavelet transform is used. The experimental results show that we can reach an average hiding capacity of 34.5% over different music and speech signals. The quality of steganography process in terms of signal to noise ratio (SNR) and mean opinion score (MOS) is considered suitable and achieved as 76 dB and more than 4.7, respectively.