Technologies 2014, 2(1), 31-53; doi:10.3390/technologies2010031
Review

Local Control of Audio Environment: A Review of Methods and Applications

Received: 22 December 2013; in revised form: 16 January 2014 / Accepted: 22 January 2014 / Published: 10 February 2014
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: The concept of a local audio environment is to have sound playback locally restricted such that, ideally, adjacent regions of an indoor or outdoor space could exhibit their own individual audio content without interfering with each other. This would enable people to listen to their content of choice without disturbing others next to them, yet, without any headphones to block conversation. In practice, perfect sound containment in free air cannot be attained, but a local audio environment can still be satisfactorily approximated using directional speakers. Directional speakers may be based on regular audible frequencies or they may employ modulated ultrasound. Planar, parabolic, and array form factors are commonly used. The directivity of a speaker improves as its surface area and sound frequency increases, making these the main design factors for directional audio systems. Even directional speakers radiate some sound outside the main beam, and sound can also reflect from objects. Therefore, directional speaker systems perform best when there is enough ambient noise to mask the leaking sound. Possible areas of application for local audio include information and advertisement audio feed in commercial facilities, guiding and narration in museums and exhibitions, office space personalization, control room messaging, rehabilitation environments, and entertainment audio systems.
Keywords: local control of audio environment; directional speaker; parabolic speaker; flat panel speaker; ultrasonic speaker
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MDPI and ACS Style

Kuutti, J.; Leiwo, J.; Sepponen, R.E. Local Control of Audio Environment: A Review of Methods and Applications. Technologies 2014, 2, 31-53.

AMA Style

Kuutti J, Leiwo J, Sepponen RE. Local Control of Audio Environment: A Review of Methods and Applications. Technologies. 2014; 2(1):31-53.

Chicago/Turabian Style

Kuutti, Jussi; Leiwo, Juhana; Sepponen, Raimo E. 2014. "Local Control of Audio Environment: A Review of Methods and Applications." Technologies 2, no. 1: 31-53.

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