audio

Audio refers to sound as it is heard, recorded, transmitted, or processed in electronic systems. It encompasses the techniques, technologies, and materials used to produce and reproduce sound.

Sound is a mechanical wave produced by vibrating objects and propagating through media such as air or water. In human hearing, frequencies roughly from 20 Hz to 20 kHz are perceptible, with amplitude related to loudness. Sound intensity is measured in decibels.

Audio signals can be analog or digital. Analog audio varies continuously in time, while digital audio samples the waveform at a sampling rate and stores amplitude as discrete values. Common sampling rates include 44.1 kHz and 48 kHz; bit depth such as 16-bit or 24-bit affects dynamic range.

In recording and playback, microphones convert acoustic energy to electrical signals; audio interfaces, preamplifiers, processors, and storage devices handle the signal, which is ultimately converted back to sound by loudspeakers or headphones. Digital processing enables editing, effects, mixing, and mastering.

Formats and standards define how audio data are encoded. Uncompressed formats such as PCM-based WAV or AIFF preserve original quality; compressed formats include lossless codecs like FLAC and ALAC, and lossy codecs such as MP3 and AAC. Codecs rely on psychoacoustics to reduce data while preserving perceived quality.

Applications span music production, broadcasting, telecommunications, film and video, and multimedia systems, as well as emerging areas like immersive audio and virtual reality.