By far, the most widely used subjects in psychological and biological
research today are rodents. Although rats and mice comprise the largest
group of animals used in research, there are over 2,000 species and 27
families of rodents, living all over the world (except Antarctica) and
thriving in many different habitat types. The vast environmental
diversity that rodents face has led to numerous adaptations for
communication, including vocalizing and hearing in both the sonic and
ultrasonic ranges, effectively communicating in the open air and
underground, and using vocalizations for coordinating sexual behavior,
for mother-pup interactions, and for signaling an alarming situation to
the group. Some rodent species have even developed foot drumming
behaviors for communication. Comparative studies from around the globe,
using both field and laboratory methodologies, reveal the vast
differences in acoustic communication behavior across many rodent
species.
Some rodents are amenable to training and have been domesticated and
bred purely for research purposes. Since the early 1900s, rats and mice
have been indispensable to research programs around the world. Thus,
much of what we know about hearing and vocalizations in rodents come
from these two species tested in the laboratory. The sequencing of the
mouse genome in 2002, followed by the rat genome in 2004, only increased
the utility of these animals as research subjects since genetically
engineered strains mimicking human diseases and disorders could be
developed more easily. In the laboratory, rats and mice are used as
models for human communication and hearing disorders and are involved in
studies on hearing loss and prevention, hormones, and auditory
plasticity, to name a few. We know that certain strains of mice retain
hearing better than others throughout their lifespan, and about the
genes involved in those differences. We know about the effects of noise,
hormones, sex, aging, and circadian rhythms on hearing in mice and other
rodents. We also know about normal hearing in many families of rodents,
including the perception of simple and complex stimuli and the anatomy
and physiology of hearing and sound localization.
The importance of acoustic communication to these animals, as well as
the significance of these mammals to biomedical research, are summarized
in the chapters.
