Steganography is the art and science of writing hidden messages such that the existence of a secret communication is known only to the sender and receiver. For hiding messages different types of media are used. Audio steganography uses audio as the cover media. Commonly used techniques for audio steganography are temporal domain and transform domain techniques, where the frequency domain techniques and wavelet domain techniques come under transform domain. Under temporal domain the techniques include LSB encoding, parity coding and echo hiding. Under frequency domain the different techniques are tone insertion, phase coding and spread spectrum technique. This paper makes a discussion on audio steganography techniques. Among the techniques studied wavelet domain shows high hiding capacity and transparency. In wavelet domain different techniques are applied on the wavelet coefficients to increase the hiding capacity and perceptual transparency. The paper mainly concentrates on a survey on audio steganography in wavelet domain.