SoX is a command line utility that can convert various formats of computer audio files in to other formats。 ex1: convert 16k 16bit pcm file to 8k 、8 bit ulaw file sox -t raw -r 16000 -2 -s -c 1 src.pcm -t raw -U -r 8000 dest.ulaw ex2: merge files sox -t raw -s -2