What is the difference between sound and audio? I often hear people confuse the terms. Here are a couple of ways of thinking about the difference.
A good summary can be found in this blog post:
- Sound is vibrations through materials
- Audio is the technology to hear sounds coming from natural or human-made sources
Another good definition is that audio is electrical energy (active or potential) that represents sound. From this, a sound recording is stored as an audio file. It is important to note that we are not only talking about digital audio files. Audio can also be stored on an analog medium, such as an LP or cassette, from which it can be used to play back sound.
Schematically, one can think of audio as the part between a microphone and a speaker, with sound on each side. Here this is illustrated as a modification of figure 9.4 from my book Sound Actions:
Another way of thinking about the difference between sound and audio is to consider the difference between light and video. A video file essentially records visible light, that is, the electromagnetic radiation that the human eye can perceive. Light and sound are physical entities (radiation and waves) that can be captured through video and audio.