Communication Theories - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 86

Endler ( 1992 ) has defined sensory driver as the process that integrates environ-
mental physics, biophysics, and neurobiology and has depicted some general rules
for signaling with sound.

1. Use lower frequencies ( 2 kHz) in order to minimize reverberation, attenua-

tion, and scattering by the atmosphere, objects, and “shadows” resulting from
temperature gradients.
Do not use frequencies that are to low (

<

0.5-1 kHz) to minimize destructive
interference and to avoid energetically costly coupling between low-frequency
sound generation and the atmosphere.
2. Send signals from a position that is greater than 1 m above the ground and
preferably upwind of the receiver, in order to minimize destructive interference
from ground reflection and temperature gradient effects.
3. Avoid rapid syllable repetition rates in places (such as forests) with strong
reverberation.
4. Use frequency modulation rather than amplitude modulation because reverber-
ation and turbulence modify sound amplitude more than frequency.
5. Use redundant signal structure in order to average out background noise.
6. Use greater amplitude and/or physical structure to beam the signal more
effectively.
7. Use higher frequencies if much information must be transmitted in a short time,
because receptors have a faster frequency response at higher frequencies and
there will be less degradation by turbulence.
8. Use species-specific frequency bands and tuned receptors in order to minimize
noise at other frequencies.
9. Choose frequency bands, places, seasons, and times of day that minimize
turbulence and/or background noise.
10. Avoid signaling at the same time as immediate neighbors (unless jamming their
signals is desired).
11. Use rapidly degrading signals for short-distance communication and slowly
degrading signals for long-distance communication.
12. Use simpler, more effective alerting signals to attract the receiver's attention
before sending the main signal.

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4.12 The Honesty of Acoustical Signals

Acoustic communication in birds has at least two major functions: defending the
territory and attracting females. There are other functions such as social cohesion,
cooperation, but generally the majority of the investigations have been carried out
exploring the competition domain and sexual selection (see Gil and Gahr 2002 for a
review).
In birds, song quality becomes a fundamental factor in sexual selection and in
mating success. The physical condition of a male is connected to the quality of song