University of Hertfordshire

By the same authors

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Original languageEnglish
Publication statusUnpublished - 1 Nov 2019

Abstract

It sounds great in my studio. Why doesn’t it sound the same for my public-art project…? The author has developed technical and aesthetic solutions for audio reproduction in public-art site-specific spaces where listening conditions and acoustics may not be at their optimum.

Basic loudspeaker stereo (Blumlein Stereo) uses two loudspeakers. This has become the standard system for the majority of commercial listening (still exceeding commercial ‘surround sound’ systems such as 5.1). With stereo, it becomes possible to create one of the most magical things in sonic art – the phantom image. It is uniformly accepted that the optimum configuration for positioning of listener to loudspeakers is an equilateral triangle, with the listener observing equidistant from both loudspeakers (the sweet-spot). Whilst this is fine for independent listening in a home or studio environment, the sweet-spot is not achievable in a public-art environment in the majority of cases (there will be multiple listeners, and they may be moving). With more than two speakers (quad, 5.1, 8.1, 10.2, 16.4…), this is a significant problem that is often ignored.

Point Source localization
The sweet spot issue encountered with basic stereo results from the sound of one loudspeaker being masked by the sound of the other. If the listener is closer to one loudspeaker, they will not be able to hear the output of the other. However, the listener can hear the sound of all loudspeakers, no matter their location, if they are treated as point sources. This means, when a sound is coming out of one loudspeaker, it isn’t coming out of the other. In this way, it allows an audience (no matter of their location), the opportunity of hearing all sounds from all loudspeakers (as masking doesn’t occur).

Movement from loudspeaker to loudspeaker in such a way will produce abrupt changes of localization. Whilst this may be considered a problem, or a ‘feature’, there are solutions. More loudspeakers, placed closer together, will create smoother transitions of movement. But potentially most aesthetically interesting, if the rate of change from one loudspeaker to another is fast enough, then a granulated space is produced forming a convincing immersive sound. This method of producing rapid multichannel granulated sound was produced by the author for Cosmoscope and Anarchy in the Organism in an attempt to solve a common problem in public-art audio.

Material initially delivered at Cafe Scientifique, Hatfield UK November 2019

ID: 17808232