Biology Reference
In-Depth Information
The use of sound to orient a broad suite of crustaceans has been demonstrated to
be a widespread process, and its degradation by noise pollution should create
concern in decision makers and politicians to defend marine biology.
6.17 Noise from a Multi-source Environment
When in the environment there are many sounds, people often are able to select speech
of interest from the so-called cocktail party (Cherry
1953
and Pollack and Pickett
1958
; see also Litovsky
2012
). This ability to segregate speech from other masking
sounds is not limited to humans: other nonhuman animals probably experience this
capacity, although information on this point is scant. Sounds can be better distin-
guished when they are spaced (separate in space) than when they are co-localized.
The problem of distinguishing, in a multi-source environment, the correct sound
probably has been an evolutionary constraint along the evolutionary path in many
animals.
In humans has been verified the capacity to distinguish different speeches by a
“spatial release from masking” (SRM) of 6-10 dB when separated by an angle of
90
. To verified this property in nonhuman animals, Nityananda and Bee (
2012
)
have investigated the SRM in the Cope's gray treefrog (
Hyla chrysoscelis
).
In this species, as in many other amphibians, the female must localize a calling
male inside a noisy social environment created by several contemporary calls of
other competing males.
Experiments have demonstrated that this species has a SRM of 3 dB when the
masker was displaced 90
in azimuth from the target and the value of SRM was
independent from the spectral composition. In conclusion, the SRM contributes to
solving the “cocktail party-like” problem of a female that must recognize a male in
a very biologically noisy environment.
6.18 Oil Spills, Noise, and Effects on Animals
The effects of human activities on animal populations of wild areas are evaluated
generally in term of abundance and distribution. In reality, however, local effects
create modification of behavior and of reproductive activity as well. Short-term
changes in behavior can produce on a larger time scale effects on abundance and
distribution, and consequently it seems important to have access to this information
in time to modify policies and management strategies. The acoustic method allows
detecting local subtle changes in behavior that may have effects on long-term and
large spatial range.
The extraction of natural resources such as gas, oil, and minerals requires
geophysics prospecting by the use of dynamite detonation and the increased
presence of people in remote areas. In the marine environment, seismic shooting
with air-guns is used to map oil and gas resources.
Search WWH ::
Custom Search