Biology Reference
In-Depth Information
To limit the annoyance effects of the wind turbines, their noise has been entered
into an emission regulation protocol. For instance, in Germany a noise of 45 dB is
allowed. This tradeoff could be modified because the limitation of the power by a
turbine during strong wind could be masked by the noise of wind itself.
Noise level changes greatly in different countries according to the character of
the landscapes. If the wind turbines are functioning in suboptimal regime to respect
the noise regulation, this requires a displacement of a major number of turbines per
unit of surface. In the UK the noise of turbines is assessed 5 dB higher than the
environmental noise level at different wind speeds. This approach seems very
interesting because the noise limit is adaptive, but it is expensive to have data for
each turbine to calculate the possible noise.
6.20 Military Noise
Few studies are concerned with military noise. The major source of noise in
peacetime is represented by fixed-wing aircraft (sonic boom, turbine noise, propel-
ler noise, exploding bombs/missiles), helicopters (rotary-wing aircraft: rotor blade,
turbine), tanks (engine and road noise), artillery, guns (muzzle blast, shock wave of
projectile, explosion) (airborne and substrate-born), and infantry (small arms).
The concern is that most of the military noise goes on in wild areas far from
people and urban settlements, and this can cause great
impacts on animal
populations.
The effect of military noise covers a broad spectrum of processes and dynamics.
Animals are really impacted by military activity at ground level when the move-
ment of tanks and infantry is accompanied by explosions of bombs, artillery, and
rifles. The amount of sound level of a small projectile (60 g TNT) exploding
generates a peak of 144 dB, and a larger projectile of 20 kg TNT has a peak of
163 dB at 100 m distance.
Blast noise represents an impulse noise with a shock wave that can be
>
150 dB SPL.
Further research is necessary, but military noise, excluding the blasts, is not
different from civilian vehicle-borne noise.
6.21 A Psychoacoustic Approach to Noise
The perception of the everyday world is an exceedingly complicated phenomenon,
and especially the perception of sound, which is an omnipresent source of informa-
tion and a signal per se, cannot be voluntarily excluded by our sensorial input
process. In fact, sounds are perceived when our mind is immersed in other fields of
cognition; in other words, we cannot switch off the sound sensations. This fact
has great consequences on everyday life, and a sound assessment requires not
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