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noise exposure and perceived health in these children, but no definitive
conclusions can be drawn. Children that denied annoyance reported more
symptoms than children without annoyance. Annoyance produces a reduction
of blood pressure, but in the children investigated in this project there were no
differences between blood pressure of annoyed and unannoyed children.
In urban areas especially noise is the result of multiple sources of sound (e.g.,
aircraft, motor vehicles, trains, boom cars, car horns, car alarms, sirens). The
negative effects on health seem more the result of the combination of different
sources than the effect of a specific noise. In particular, a low-frequency noise
that is pervasive, accompanied by a more efficient propagation, is difficult to be
mitigated or reduced. This low-frequency noise that
is underestimated by
measurements may have severe consequences on health.
The World Health Organization (WHO) has produced important guidelines
for dwellings, schools and preschools, hospitals, for industrial, commercial,
shopping, and traffic areas, for ceremonies, festivals, and entertainment events,
and the use of headphones or music, impulse sounds from toys, fireworks, and
firearms.
6.26 Urban Soundscape Design for Biodiversity
As argued by Katti and Warren ( 2004 ), the urban environment represents a chal-
lenge for integration between humans and nature. Urban noise offers a unique
opportunity for great experimentation on how a signal changes under the pressure
of such a dynamic sonic environment. Urban means heterogeneous in space and
time for the distribution of houses, roads, gardens, parks, etc. This heterogeneity is
found also in the soundscape, which creates new conditions in which species can
evolve and adapt coping cultural and genetic mechanisms. The adaptation of
species to the urban environment can suffer physiological constraints such as the
impossibility of changing the frequency or suffering from the shift in acoustic
rhythms to escape the masking effect of noise. These adaptations simultaneously
could produce desynchronization of mating or increased exposure to predators.
In a recent investigation in 27 urban parks of cities and villages across Spain and
Portugal, Paton et al. ( 2012 ) have found that of the 91 species of birds found in the
urban parks at least 10 ( Regulus regulus , Streptopelia turtur , Dendrocopos minor ,
Buteo buteo , Hirundo daurica , Corvus corax , Oriolus oriolus , Cettia cetti , Passer
hispaniolensis , Sylvia melanocephala ) seem affected by noise level and that a
reduced value of noise (below 50 dB) can allow the presence in the urban parks
of rare species (Fig. 6.19 ). The authors conclude that the reduction of urban noise
could open a new era of biodiversity conservation in urban green areas. In fact,
modern urban ecosystems, because of their intrinsic heterogeneity that reflects the
great surface occupied, are attractive to a growing number of synanthropic animals.
Animal communication is affected by urban noise only when the intensity is high,
but when this value is medium or low, adaptive mechanisms prevail.
For instance, from the different reactions that animals have to incorporate the
effect of noise in the communication system, the shift of frequency has been the one
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