What is Audio Steganography?

Audio steganography is an approach of hiding information within an audio signal. As data is embedded in the signal, it gets changed. This modification should be create indistinguishable to the human ear.

Image can also be taken as a medium but audio steganography is more impressive because of the features of Human Auditory System (HAS) like large power, powerful range of hearing and high range of audible frequency.

Cryptography includes the encryption of message. It creates no attempt to conceal the encrypted message. In steganography, the original message is not changed but the very continuation is secret from the intruder by embedding the message in the selected medium.

An audio environment is decided by two considerations such as first, its digital description and second, its transmission media. Digital audio files have two main characteristics which are as follows −

  • Sample quantisation rate − This is a 16-bit linear quantisation and defines highquality digital audio, including those utilized by WAV files.

  • Temporal sampling rate − This can establish an upper bound on the usable area of the frequency range. The well-known ones contains 8 kHz, 9.6 kHz and so on, up to 44.1 kHz.

The transmission channel of an audio signal define the environments the signal can go through, on its method from encoder to decoder. This can be digital end-end, analog transmission, and increasing-decreasing resampling or “over-the-air” environments.

A famous audio steganography approach is the LSB (Least Significant Bit) algorithm. In this, the least significant bit of the cover signal can be used to hide the message. This is a very simple method. The changes create to the LSB bit will not be reflected in the last stego signal.

Modifications are completed to the existing LSB method to enhance security. Few of such approaches are defined in this study. Apart from security, there are specific other parameters such as time complexity, computational load, SNR (Signal to Noise Ratio), BER (Bit Error Rate), efficiency, etc. are to be treated for Audio Steganography.

LSB acquire advantages like low computational load and simplicity yet drawback in security. Therefore Enhanced Audio Steganography (EAS) with more layers of encryption and decryption can be performed. Here before encoding the information, it is encrypted.

The main characteristics of EAS are the size of the file is not modified after encoding and there is no software available to decide the sound variation generated by bit level manipulations.

Data is embedded in such a method that each character needed eight 254/255 bytes. Frequency chart analysis display that the effectiveness of the algorithm in terms of security is the benefit of this approach and the constraint is that sound quality depends upon the size of the audio selected and length of message embedded. This also provides some audio format.