This book constitutes the refereed proceedings of the 18th National Conference on Man-Machine Speech Communication, NCMMSC 2023, held in Suzhou, China, during December 8-11, 2023. The  20 full papers and 11 short papers included in this book were carefully reviewed and selected from 117 submissions. They deal with topics such as speech recognition, synthesis, enhancement and coding, audio/music/singing synthesis, avatar, speaker recognition and verification, human-computer dialogue systems, large language models as well as phonetic and linguistic topics such as speech prosody analysis, pathological speech analysis, experimental phonetics, acoustic scene classification.