Digital sound — Computing, 4–6
A computer can turn a sound into stored measurements and turn them back into sound. Computing, 4–6 years.
Sound as measurements
A microphone notices how the air moves when you speak, clap or sing. A computer records many tiny measurements of that movement as numbers. When a speaker uses those numbers, the air moves again and you hear a copy of the sound.
Why record sound?
A live sound disappears when the moment ends. People wanted to hear a song, a voice or a warning again, and send it to someone far away. Turning sound into numbers lets a computer store it, copy it and play it later.
Recording a clap
You clap once near a tablet. First, its microphone detects the air movement. Next, the tablet changes that movement into numbers and stores them. When you press play, the numbers control the speaker, which moves the air and makes a clap-like sound. A real clap happened only once.
A recording is not the sound itself
It is easy to think a recording contains the original sound trapped inside. That makes sense because it can sound very similar when played. Actually, it contains measurements that help a speaker recreate the sound, so the recording may be quieter or slightly different.
Sound recordings outside school
Digital sound is in voice messages, audiobooks, music players and doorbells that speak. It helps people save a story or send a message when they cannot talk at the same time. The microphone and speaker still need real air moving, so sound is not made from numbers alone.
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