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habituation than NNS subjects. Women subjected to repeated sounds of 50, 75, and
100 dB (A-weighted) had a slower habituation threshold when the sounds were
repeated.
In NS the distractibility is higher than in NNS. When moderately loud sound are
submitted to NS people the annoyance and unpleasantness are considered greater.
NS People exposed to road traffic noise declared a higher annoyance than NNS
people at a low level but converged when the intensity was increased.
The NS becomes a physiological status that may have important consequences
on the choice for such individuals of a place in which to live (see Luz
2005
).
Considering that 22 % of a urban population may be affected by the NS condition,
diffuse noise in most urban metropolitan areas represents a relevant problems for
many people.
Noise sensitivity is not related to noise exposure: NS alters the effect of noise
exposure on noise annoyance and has not simply an additive effect. In an experi-
ment Miedema and Vos (
2003
) investigated the effect of aircraft traffic noise
exposure. Noise sensitivity was found to change the influence of noise exposure
on noise annoyance. Subjects with NS have a predisposition to discriminate envi-
ronmental conditions and to evaluate them, but this attitude is weak in NNS.
Age seems a discriminant for noise annoyance. An investigation conducted by
Van Gerven et al. (
2009
) in a Dutch sample and in a specific data set (Amsterdam
Airport Schiphol) of total 62,893 individuals aged between 15 and 102 years
demonstrated that noise sensitivity had a curvilinear distribution with a maximum
around 45 years, and a minimum was found between youngest and oldest age
segment (Fig.
5.2
). This patterns is independent from noise exposure and self-
reported noise sensitivity. The large data set and its internationality assures the
significance of the results and the intercultural effects. It seems a surprise that the
people who should be more resilient to noise are at the same time the most
vulnerable.
5.4 Noise Annoyance: Definition and Evaluation
Procedures
Annoyance is defined as a feeling of displeasure evoked by noise (Berglund
et al.
2002
). This parameter is used not only to evaluate the effect of noise on
sleeping function but also for other adverse effects of noise. Many researches have
confirmed that annoyance is correlated with the (perceived) loudness and the sound
pressure level.
For instance, personal and situational variables were considered by Fields (
1993
)
in the evaluation of noise annoyance in residential areas. According to this author
noise annoyance is not caused by ambient noise levels or by the amount of time
residents are at home, the type of interviewing method, or the demographic
variables (age, sex, social status, income, education, home ownership, type of
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