Communication Theories - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 63

4.2 The Communication Theory
We can admit that a general theory should exist to provide a framework in which to
place the different epistemic objects that are adopted in the acoustic realm and in
communication.
Communication has been an extraordinary event in the history of evolution
(Margoliash and Hale 2008 ). Communication consists in the transfer of signals
from an emitter that convey information to a receiver.
This theory can be explained adopting a biosemiotics approach, although more
recently code biology, which represents an innovative perspective to investigate
and interpret the communicative process, offers a new theoretical support.
The communicative process probably has been submitted to an evolutionary
process by which the signals have been improved in terms of efficiency of commu-
nication and reliability of manipulation by the receiver. On the other end, the
receiver mechanisms have evolved with increasing reliability and efficiency of
information reception. The reception of the signals must be sufficiently clear and
distinct to produce in the receiver the requested behavioral or physiological
decision.
During the transfer, part of the signal is modified by the effect of environmental
constraints (absorption, distortion, interference) and minimization of reception by
emitter exploiters (Xe) (predators, signal-homing parasites). To receive the signal
in the most efficient way, the receiver must filter the noise present with in the
information channel, must reduce the effects of subsidiary emitter (Es) and receiver
exploiters (Xr) such as Batesian mimics or males with inferior genes (Endler 1993 ).
Signal generation represents the first step in the signaling process. The evolution
of a signal depends on physical, chemical, and biophysical constraints. To produce
biological signals is always energetically costly and time consuming, and, for
instance, there is empirical evidence of such energetic cost in frogs and birds. To
reduce such cost, a specific singing design can be produced with the effort of
muscles involved in the singing process, but timing, intensity, and form of signals
can come under the selective pressure of other environmental factors. Generally a
trade-off between complexity, reliability, and efficiency is achieved.
Several factors affect signals during communication:
Signal generation and emission (biophysical limits energetic limits, biochemical
limits, energy storage, timing and location, environmental effects on emission,
information content versus clarity, information density of rate, genetic variation)
Transmission through the medium (background noise, interfering signals, attenua-
tion, blocking, absorption, reflection and refraction, distance, spectral properties,
temperature, self-interference, information density, timing, and location)
Signal reception and processing (biophysical and biochemical limits to reception,
sensory adaptive state and attentiveness, need to be attentive, need for alerting
signals, short reception time, other signals, noise, jamming, signal reception rate,
information processing rate, pattern recognition needs)