BIEB 166 Lecture Notes - Lecture 14: Rayleigh Wave, Infrasound, Transverse Wave
8 Nov 2013
School
Department
Course
Professor
Document Summary
Sound is the propagation of a local perturbation in molecular density. Sound is detected by comparing local pressure exerted by medium molecules relative to that of some ambient reference level (ears and microphones do this) This spatial distribution of deviations from ambient pressure levels at any given instant of time is called the sound field. Molecules of air moving near the sound source when sound is produced (i. e. hitting a drum) Short distance away, the air molecule motions are translated to pressure. The molecules will no longer travelling any appreciable distance (now vibrating) Rapidly absorbed by the environment (doesn"t transmit very far) Frequencies are too low for human to detect. They lift up their legs when they generate sound. The infrasound may perceive through substrate, and being picked up in part through the legs of the animal. Cheeks are vibrating when the females are ready to mate. Elephant female has a very long gestation period.
