View source for Audio signal

{{short description|Representation of sound, typically as an electrical voltage}}
{{One source|date=August 2020}}

An '''audio signal''' is a representation of [[sound]], typically using either a changing level of electrical [[voltage]] for [[analog signal]]s, or a series of [[binary numbers]] for [[Digital signal (signal processing)|digital signal]]s. Audio signals have frequencies in the [[audio frequency]] range of roughly 20 to 20,000&nbsp;Hz, which corresponds to the lower and upper [[Human hearing range|limits of human hearing]]. Audio signals may be [[Synthesizer|synthesized]] directly, or may originate at a [[transducer]] such as a [[microphone]], [[Pickup (music technology)|musical instrument pickup]], [[phonograph cartridge]], or [[tape head]]. [[Loudspeaker]]s or [[headphones]] convert an electrical audio signal back into sound.

[[Digital audio]] systems represent audio signals in a variety of digital formats.<ref>Hodgson, Jay (2010). ''Understanding Records'', p.1. {{ISBN|978-1-4411-5607-5}}.</ref>

An '''audio channel''' or '''audio track''' is an audio signal [[communications channel]] in a [[data storage device|storage device]] or [[mixing console]].  It is used in operations such as [[multi-track recording]] and [[sound reinforcement]].

== Signal flow ==
[[Signal flow]] is the path an audio signal will take from source to the speaker or recording device. Signal flow may be short and simple as in a [[home audio]] system or long and convoluted in a [[recording studio]] and larger sound reinforcement system as the signal may pass through many sections of a large mixing console, external [[audio equipment]], and even different rooms.

==Parameters==
Audio signals may be characterized by parameters such as their [[Bandwidth (signal processing)|bandwidth]], [[nominal level]], [[Electric power|power]] level in [[decibel]]s (dB), and voltage level. The relationship between power and voltage is determined by the [[Electrical impedance|impedance]] of the signal path. Signal paths may be [[Single-ended signalling|single-ended]] or [[Balanced audio|balanced]].

Audio signals have somewhat standardized levels depending on the application. Outputs of professional mixing consoles are most commonly at [[line level]]. Consumer audio equipment will also output at a lower line level. Microphones generally output at an even lower level, known as ''mic level''.

== Digital equivalent ==
The digital form of an audio signal is used in [[audio plug-in]]s and [[digital audio workstation]] (DAW) software. The digital information passing through the DAW (i.e. from an audio track through a plug-in and out a hardware output) is an audio signal.

A digital audio signal can be sent over [[optical fiber]], [[coaxial]] and [[twisted pair]] cable. A [[line code]] and potentially a [[communication protocol]] are applied to render a digital signal for a transmission medium. Digital audio transports include [[ADAT]], [[TDIF]], [[TOSLINK]], [[S/PDIF]], [[AES3]], [[MADI]], [[audio over Ethernet]] and [[audio over IP]].

==See also==
{{div col|colwidth=20em}}
*[[Analog recording]]
*[[Audio editing software]]
*[[Audio engineer]]
*[[Audio signal processing]]
*[[Digital recording]]
*[[Equalization (audio)]]
*[[Professional audio]]
*[[Psychoacoustics]]
*[[Sound intensity]]
*[[Sound recording and reproduction]]
*[[Stereophonic sound]]
*[[Surround sound]]
{{div col end}}

==References==
{{reflist}}

==External links==
*{{Commons category-inline|Audio signal}}

[[Category:Musical terminology]]
[[Category:Sound production technology]]
[[Category:Audio engineering]]