Transactions on Machine Intelligence 2821-1693 4 3 2021 09 01 Concealment of Speech Signals within Speech by Combining Cryptography and Steganography 109 117 209215 10.47176/TMI.2021.109 EN J. Shirazi Assistant Professor, Department of Electrical Engineering, Gonabad Branch, Islamic Azad University, Razavi Khorasan, Gonabad, Iran Journal Article 2021 06 04 The concealment of speech signals, particularly within other speech signals, encompasses the integration of cryptographic techniques and steganographic methods. This literature review synthesizes current research findings and identifies existing gaps in knowledge, while also suggesting potential future research directions. In this paper, to enhance data security in speech transmission, a combination of steganography and cryptography is utilized. In the encryption phase, the Discrete Cosine Transform (DCT) is applied to frames of the speech signal. This phase involves scrambling time-domain samples, transform coefficients, and time-domain samples obtained from the inverse transform of the signal using a chaotic function that generates random numbers. In the steganography phase, the encrypted data replaces the low-value coefficients of the Discrete Wavelet Transform (DWT) of the host speech signal. To evaluate the proposed hybrid method, both qualitative and quantitative metrics were used. The results indicate a high level of various metric measures for the method. https://www.tmachineintelligence.ir/article_209215_d5a4052636c4fa68d93e3bac077abc18.pdf