WhatIs.com

audio

By Robert Sheldon

What is audio?

Audio is sound that is within the acoustic range of human hearing. It is the audible portion on the spectrum of sound frequencies, distinct from inaudible sounds heard by certain animals or used in science and medicine. An elephant, for example, can hear sounds at lower frequencies than humans, and porpoises can hear sounds at higher frequencies. In both cases, they hear sounds that fall outside the range of human hearing.

Sound is a form of mechanical energy that travels in waves through air and other substances. It is measured in hertz (Hz), with one Hz equal to one full wave cycle per second. Humans can hear only a portion of the full spectrum of sound frequencies. The audio portion is typically between 20 to 20,000 Hz, but aging and hearing damage can shorten this range.

Although audio has a distinct meaning in relation to sound, the term is often associated with computing and other electronic devices. Within this context, audio refers to the field of technology concerned with recording, processing, storing and delivering audible sound using electricity. Most computers, for example, now support vocal interaction through a microphone audio file, can store and run sound audio files in multiple formats, and can deliver sounds through speakers or headphones. These features represent a computer's audio capabilities.

How is audible sound produced and transmitted?

Audible sound is produced by using electricity and is transmitted as either analog or digital signals:

How is digital audio content stored?

Today, most audio content is stored as digital data, even if its original storage format is analog, as is often the case in professional recording studios. The digital trend has given rise to a wide range of audio file types, such as those shown in the table:

File type Compressed Lossless

Advanced Audio Coding (AAC)

Yes

No

Apple Lossless Audio Codec (ALAC)

Yes

Yes

Audio Interchange File Format (AIFF)

No

Yes

Free Lossless Audio Codec (FLAC)

Yes

Yes

MPEG-1 Audio Layer 3 (MP3)

Yes

No

Ogg Vorbis (OGG)

Yes

No

Pulse-Code Modulation (PCM)

No

Yes

Waveform Audio File Format (WAV)

No

Yes

Windows Media Audio (WMA)

Yes

No

Windows Media Audio Lossless (WMA Lossless)

Yes

Yes

The Compressed column indicates whether the data is compressed when stored in the specific file format. The Lossless column indicates whether data is lost from its original uncompressed state when converted to that format. If the file type is lossless, the data is preserved, otherwise it is considered lossy, which can affect sound quality.

The table does not show all audio file types; however, the ones included here represent the more common types in use today. These formats also illustrate the variety of file types supported by the audio industry, a list that continues to evolve as the industry enhances and introduces new technologies.

See also: audio frequency, dynamic range, harmonic, A-weighted decibel, bone conduction headphones, sample rate and latency

02 Dec 2022

All Rights Reserved, Copyright 1999 - 2024, TechTarget | Read our Privacy Statement