Asteroids · Arcade · 1979 · Ambient Loop · Wendi Allen
Two low notes, alternating, getting faster. Asteroids had no music and no sound chip, and its throbbing heartbeat still did more to raise a player's pulse than most soundtracks.
Atari's Asteroids, released in North America in November 1979, was conceived by Lyle Rains and programmed by Ed Logg on vector hardware developed by the engineer Wendi Allen. The machine had no sound chip. Instead Allen built a hardware circuit for its thirteen sound effects by hand and wired it onto the board — the ship's thrust, the shots, the explosions of rocks and the flying saucers. The most memorable of them is barely a sound effect at all. Under the action runs a "heartbeat": a pair of low, alternating tones, like a slow two-note bass line. As a wave goes on, the heartbeat quickens. It is the same principle that had made Space Invaders' descending march so effective a year earlier — tempo tied to the state of the game — but in Asteroids it works almost subliminally. The player is concentrating on rocks, bullets and the inertia of the ship, and the rising tempo registers as tension rather than as music. When a new wave begins, it slows again, and the relief is audible.
The heartbeat does not tell the player anything they could not see. Its job is emotional: it turns the gradual pressure of a wave into something the body feels. Because it is so simple — two notes, no melody — it never competes with the sound effects for attention, and it never becomes a tune the player tunes out.
It is one of the earliest examples of a game adjusting its audio to its own state, a technique that would later grow into dynamic scores and adaptive music. In 1979 it was done with a few hand-wired components, and it still works.