Source-path-receiver model for airborne sounds

Abstract

The Source-Path-Receiver Model (SPRM) is a fundamental concept derived from hazard (including noise) control. It is useful in studies of animal bioacoustics where the sound sources may be animals, humans, or natural events within the habitat and the receivers are animals. It provides a framework for the researcher to ensure all aspects of the scenario being observed or recorded are considered, which could affect the observations. This chapter develops the SPRM for the example of animal acoustic communication, where the source and receiver are animals of the same species. Factors that affect the source and receiver are explained (e.g., age, sex, individual identity, and context). Much emphasis is given to "the path." The environment through which the sound travels affects the received signal (in terms of its amplitude, frequency, and duration) and exhibits ambient noise, which might affect both sender and receiver. The basic concepts of sound propagation are explained (including Huygens' principle, ray tracing, Snell's law, reflection, scattering, reverberation, diffraction, refraction, transmission, absorption, ground effect, atmosphere effects, acoustic mirages, and shadow zones). The SPRM illustrates the importance of exploring the acoustic features of a sound signal at all points between the sender and receiver to understand factors that could promote or inhibit effective communication among animals.