In recent years, extensive research has been taken for hiding data into digital audio signal because of advantages of psycho acoustical masking phenomenon of human auditory system [HAS]. This paper presents a novel method based on audio steganography by integrating optimal steganography and two level cryptographic methods. Improvement of imperceptibility of data hiding and increased security level for the secret data has been provided. In optimal steganography the random positions of the samples in audio signal are generated by a polynomial expression as a function of cover media to improve the data hiding capability. Imperceptibility of proposed method is validated using subjective and objective measures. Experimental results show that the proposed method is best suitable for hiding data in audio.