With the significant development of digital communications and networking technologies, there is need to protect the sensitive data (such as digital audio signals, images, and videos) from unauthorized access, getting leak or misused. Cryptography plays a major role within the field of network security. There are many encryption techniques available currently to secure the data. Traditional encryption such as DES and many others perform poorly for multimedia data because of the large data size and high redundancy. Due to the random-like property and high sensitivity for initial values and control parameters, hyperchaotic systems are usually proposed as a solution to data encryption. In this paper, a study on security of audio data encryption based on a new six dimensional hyperchaotic system is presented. The experimental results on audio data encryption / decryption over open networks, key sensitivity tests, and statistical analysis show that the proposed cryptosystem have excellent encryption performance, high sensitivity to the security keys and can be applied for secure real time encryption.