This article presents the performance of a MIMO MC-CDMA system using Alamouti Space Time Block Code (STBC) scheme to transmit voice signals over an AWGN channel with QAM and QPSK digital modulation scheme in terms of bit error rate (BER). According to the results of this study, QPSK modulation outperforms QAM modulation in the MIMO MC-CDMA STBC-based wireless communication system. In comparison to QPSK digital modulation, QAM digital modulation performs the worst in voice signal transmission. The present MATLAB simulation study shows that the STBC encoded 4×4 MIMO MC-CDMA wireless communication system with minimum mean square error (MMSE) signal detection and ½-rated convolution and cyclic redundancy check (CRC) channel encoding strategies perform well when transmitting voice signals using QPSK digital modulation

Keywords : MIMO, STBC, AWGN, MC-CDMA, MMSE, BER, Voice Signal Transmission.