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Fig. 5.7
Experimental
design for an audiovisual
environment in which to
experiment with sonic
ratings (Reproduced with
permission from Viollon
et al.
2002
)
(unpleasant-pleasant, stressful-relaxing). In Fig.
5.7
is shown the experimental
design to investigate the reaction of a subject to the contemporary projection of a
slide and one typology of sound. In particular, the effect of visual scenes have been
constrained by the type of sound. The subjects associated the increasing urban
setting with a more negative sound rating. For instance, birdsong and traffic noise
were judged more negatively when associated with more urban scenes. In contrast,
all the anthropogenic sounds were indifferent by co-occurring visual stimuli and
independent of the degree of urbanization contained inside the slides.
Very stressful sounds such as road traffic and very relaxing sounds such as bird
choruses were significantly influenced by the visual degree of urbanization.
These authors have found a negative correlation to be increasing between a more
urban visual environment and the rating at which the sound is interpreted.
The acoustic assessment in green areas inside urban cores is particularly impor-
tant because of the extensive use of these areas for recreational and therapeutic use.
Often the traffic noise of urban areas is not buffered from the green areas and noise
invades such areas, nullifying the recreational effect expected. Evidences of this
widespread phenomenon have been collected in a recent study by Szeremeta and
Zannin (
2009
) in a Brazilian city where from the acoustic survey of four urban
parks more than 65 % of sampled points had a sound level above the 55 dB(A) that
is the local limit fixed by the municipal law. A contemporary interview of a sampled
population in the investigated parks has demonstrated how important are the
esthetic components of the landscape in mitigating the negative effect of the
soundscape. Several factors have to be considered: environmental and urban zon-
ing, land use, traffic routes, residential streets, vegetation, type of public transpor-
tation, park typology, and sound sources coming from outside. The unpleasant
reaction of the interviewees places the soundscape in secondary importance com-
pared with water pollution and social problems (prostitution and vagrancy). The
low level of reaction from people to heavy acoustic pollution, shifting the attention
on other “visual” factors, exposes the park visitor to a high level of sound with
negative health effects.
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