Soundscape
Soundscape
To speak of a soundscape is not only to apply the characteristics of the visual landscape to the acoustic, but to consider the soundscape in its particularity. There is a fundamental difference: no sound is offscreen. The soundscape covers 360° entirely: we only see what we look at, but we hear everything around us.
SENSIVIC detectors analyse the soundscape to extract unusual sound events (gunshots, breaking windows, shocks, car accidents, ...). These are sounds that demand the attention of an operator or investigator.
Sounds used for analysis and detection are neither transmitted to the CSU nor recorded. Only alarms are produced and transmitted: privacy is fully respected.
The soundscape
To speak of a soundscape is not only to apply the characteristics of the visual landscape to the acoustic, but to consider the soundscape in its particularity. There is a fundamental difference: no sound is offscreen. The soundscape covers 360° entirely: we only see what we look at, but we hear everything around us.
We live permanently in a partially qualified sound environment. Therefore, a psychological selection mechanism is the only protection against this constant intrusion of information. The soundscape is subjective, where the visual landscape imposes itself.
The notion of soundscape was introduced into music theory by the Canadian Raymond Murray Schafer in the 1970s and is described in the seminal book, "The Soundscape, our sonic environment and the tuning of the world", published in 1977.
Like any landscape, the soundscape is built according to a certain perspective, which Schafer immediately conceives as evolving. To this end, he took up the concepts of form theory, namely the perceptual couple symbol/sense. He thus theorises the fundamental principles of the soundscape, identifying in particular the three types of sound phenomena that structure it:
Sound markers
Sound signals
Background noise
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The tonal sounds that play the role of background noise create the atmosphere. In a soundscape, the tonal sound is the one that will be superimposed on all the other sounds: the sound of the sea in a coastal town, the sound of trains passing through an apartment along a tramway line. These examples show us another characteristic of tonal sounds: they don't raise awareness. Our perception is conditioned by them, but this conditioning remains unnoticed, we only become aware of it when they stop.
Sounds with descriptive value or sound signals which play the role of a symbol. Unlike tonal sounds, the sound signal is noticed, it appears as an event for who perceives it. The sound signal often refers to something other than itself: a representation, a cause, a context.
Sound markers that reflect the same type of phenomenon but refer to a community, "which has certain qualities that make it unique, remarkable". Its status is intermediate: this type of sound is both valued by members of a community, in this regard it is similar to a sound signal, but it is also typical and familiar. It is part of the landscape. In this way it resembles tonal sounds.
Schafer's favourite example is the sound marker of his own community, Vancouver: foghorn sound.
On a practical level
What can be concluded from the above paragraphs?
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The operator should only be informed of those sound events that convey interesting information and are the most uncertain and surprising: sound signals.
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The tonal sounds do not convey any interesting information in the context of video protection: they must be eliminated from the sound activity to be reported.
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Tone markers are repetitive events: they also carry no information, in their context, that needs to be reported. They are only reported the first few times they appear (they are then sound signals) but should also be eliminated from the reportable sound activity when repetitive.
SENSIVIC smart detectors implement these principles by alerting only to sound signals.