Sound interference and diffraction is an important part of wave phenomena. Compared to the experiment on the light interference and diffraction, sound experiment is not widely performed at high schools because of the cumbersome equipment. In this experiment, we assembled an array of 256 microphones to measure the sound interference and diffraction. The sound intensity at each microphone was measured using a computer with a multiplexer and 16 analog/digital converting channels. The data were processed using MATLAB software and presented as a 3‐dimensional graphic. The diffraction experiment was done using one speaker and a wall and the interference experiment was done using two speakers. The measurement agreed with the simulation using Excel program. We hope our apparatus can be adopted for a microcomputer‐based experiment at high school physics activity.