Voice communication is closely linked to everyday life, such as education, e-learning, commerce, politics and the dissemination of information. To maintain security, sensitive data must be protected during transmission. Chaotic systems have become good candidates for cryptography to increase the degree of security. In this book, we focus on the design of a high-security voice communication system using two levels of encryption based on chaotic systems. The first level is chaotic masking, while the second level is scrambling. In the masking level using two methods, the first method is masking using a hybridization between chaotic frameworks (logistic map and tent map), while the second method is based on the Chua chaotic system. At the scrambling level, we use Arnold's map. At receiver level, we use Pecore and Carroll synchronization to recover the encrypted audio signal.