Editing Microphone array

{{Short description|Group of microphones operating in tandem}}
{{no footnotes|date=February 2019}}

[[File:Boomerang 3 Gunfire Acoustic Detection System MOD 45153048.jpg|thumb|A [[gunfire locator]] using a microphone array]]

A '''microphone array''' is any number of [[microphone]]s operating in [[tandem]]. There are many applications:

* Systems for extracting voice input from [[ambient noise level|ambient noise]] (notably [[telephone]]s, [[speech recognition]] systems, [[hearing aid]]s)
* [[Surround sound]] and related technologies
* [[Binaural recording]]
* Locating objects by sound: [[acoustic source localization]], e.g., military use to locate the source(s) of artillery fire. Aircraft location and tracking.
* [[High fidelity]] original recordings
* [[Environmental noise monitoring]]<ref>[http://www.acousticresearch.com.au/Products/Environmental%20Noise%20Compass Environmental Noise Compass]</ref>
* Robotic navigation (acoustic [[simultaneous localization and mapping|SLAM]])<ref>{{Cite journal|last1=Evers|first1=Christine|last2=Naylor|first2=Patrick A.|date=September 2018|title=Acoustic SLAM|journal=IEEE/ACM Transactions on Audio, Speech, and Language Processing|volume=26|issue=9|pages=1484–1498|doi=10.1109/TASLP.2018.2828321|issn=2329-9290|url=https://eprints.soton.ac.uk/437941/1/08340823.pdf |archive-url=https://web.archive.org/web/20200505133229/https://eprints.soton.ac.uk/437941/1/08340823.pdf |archive-date=2020-05-05 |url-status=live|doi-access=free}}</ref>

Typically, an array is made up of [[omnidirectional microphone]]s, directional microphones, or a mix of omnidirectional and directional microphones distributed about the [[perimeter]] of a space, linked to a [[computer]] that records and interprets the results into a coherent form. Arrays may also be formed using numbers of very closely spaced microphones. Given a fixed physical relationship in space between the different individual microphone transducer array elements, simultaneous DSP ([[digital signal processor]]) processing of the signals from each of the individual microphone array elements can create one or more "virtual" microphones. Different algorithms permit the creation of virtual microphones with extremely complex virtual polar patterns and even the possibility to steer the individual lobes of the virtual microphones patterns so as to home-in-on, or to reject, particular sources of sound. The application of these algorithms can produce varying levels of accuracy when calculating source level and location, and as such, care should be taken when deciding how the individual lobes of the virtual microphones are derived.<ref>{{citation |title=Assessing the accuracy of directional real-time noise monitoring systems |author=Jesse Tribby |date=9 November 2016 |url=https://www.acoustics.asn.au/conference_proceedings/AASNZ2016/papers/p124.pdf |archive-url=https://web.archive.org/web/20170316150026/http://acoustics.asn.au/conference_proceedings/AASNZ2016/papers/p124.pdf |archive-date=2017-03-16 |url-status=live |access-date=2020-05-09}}</ref>

In case the array consists of omnidirectional microphones they accept sound from all directions, so electrical signals of the microphones contain the information about the sounds coming from all directions. Joint processing of these sounds allows selecting the sound signal coming from the given direction.<ref>{{cite journal|url=http://ntv.ifmo.ru/en/article/13685/primenenie_mikrofonnyh_reshetokdlya_distancionnogo_sbora_rechevoy_informacii.htm|title=Application of microphone arrays for distant speech capture |author=Stolbov M.B.|journal=Scientific and Technical Journal of Information Technologies, Mechanics and Optics|volume=15|issue=4|pages=661–675|year=2015}}</ref>   
   
An array of 1020 microphones,<ref>[http://cag.csail.mit.edu/mic-array/ LOUD: Large acOUstic Data Array Project]</ref> the largest in the world until August 21, 2014, was built by researchers at the [[Massachusetts Institute of Technology|MIT]] [[Csail|Computer Science and Artificial Intelligence Laboratory]].

Currently the largest microphone array in the world was constructed by DLR, the German Aerospace Center, in 2024. Their array consists of 7200 microphones with an aperture of 8 m x 6 m.<ref>[https://arxiv.org/abs/2405.03322 Enhancing Aeroacoustic Wind Tunnel Studies through Massive Channel Upscaling with MEMS Microphones]</ref>

== Soundfield microphone ==
The [[soundfield microphone]] system is a well-established example of the use of a microphone array in professional sound recording.

==See also==
* [[Acoustic camera]]
* [[Acoustic source localization]]
* [[Ambisonics]]
* [[Decca tree]]
* [[Microphone]]
* [[SOSUS]]
* [[Stereophonic sound]]
* [[Surround sound]]

==Notes==
{{Reflist}}

==External links==
* [http://www.aes.org/e-lib/browse.cfm?elib=10108 Fukada's tree], in an AES paper about Multichannel Music Recording.
* [http://www.aes.org/e-lib/browse.cfm?elib=12288 Hamasaki's square], in an AES paper about Multichannel Recording Techniques.
* [https://web.archive.org/web/20100412144040/http://bebec.eu/Downloads/Beamforming_Repository/beamforming_literature.html Literature] on source localization with microphone arrays.
* [https://web.archive.org/web/20100415001954/http://www.lmsintl.com/acoustic-holography An introduction to Acoustic Holography]
* A collection of pages providing a simple introduction to [http://www.labbookpages.co.uk/audio/beamforming.html microphone array beamforming]

{{DEFAULTSORT:Microphone Array}}
[[Category:Microphone practices]]