Abstract: In a binary system for generating sound, digital signals representing an audio analog signal are stored in memory, a first voltage level is produced for a time t.sub.1 proportional to the value of a respective stored digital signal, and a second voltage level is produced for a time t.sub.2 =t.sub.c -t.sub.1, where t.sub.c is a fixed clock signal time interval. The first and second voltage levels are successively supplied to a speaker to operate the speaker in a type of frequency modulated mode to produce sound corresponding to the audio analog signal.