Cryptography has been used as a tool for safekeeping of secret information and for protecting valuable information from unpermitted access. Besides hiding the information, it is also important in some occasions to hide any relationship between the two parties incorporating in a secure communication. The science of hiding a message in a cover media (such as audio, video and image) is generally known as steganography. Steganography along with cryptography can provide a high level of security for information exchange. Steganalysis methods have been developed to counteract the steganography methods. These methods try to find the existence of hidden information in cover media. The development of steganography in digital media was started from 1994 when a paper was published on hiding information in least significant bits of cover media. After 9/11 terrorist attack and the possibility of using steganography by the terrorist groups, steganography and steganalysis was regarded with more attention and the first methods of steganalysis were developed. New methods for steganography and steganalysis are being developed rapidly and grow up in a counteracting environment. Different methods of steganography in digital media can be categorized in different ways. One of the categorizations is based on the cover media type. The cover object can be one of the different types of digital media such as video, audio or image. One of the most important factors in steganography is the embedding efficiency of the steganography plan which is defined as ratio of the embedded bits in the cover object to sample changes in the media. Different methods have already been proposed for increasing embedding efficiency. However, increasing embedding efficiency in audio steganography is still a challenging problem. In this thesis, after reviewing of different methods of audio steganography, a new steganography method with high embedding efficiency is proposed. The proposed method increases the audio quality of the generated signal and embedding efficiency by exploiting human auditory system and decreasing the distortions caused by embedding process. The efficiency of the proposed method is measured by implementation of the method and is compared with the efficiency of existing methods. The quality of the obtained signal is also tested using the audio quality measurement model and the superiority of the proposed method over other method is verified. Keywords: Steganography, Steganalysis, Embedding efficiency, Auditory system