Bat Echolocation Research

bat detectors
frequency division
transform ultra->audible sound
heterodyne
transform ultra->audible sound
sound transmission
time expansion
transform ultra->audible sound
ultrasound detectors
ultrasound microphones
capacitance
ultrasound microphone
electret
ultrasound microphone
piezoelectric
ultrasound microphone
how will the sound wave be changed as it propagates through the transmission medium?

geometric spreading

reflection

absorption

refraction

scattering

Doppler shift

geometric spreading

— sound intensity “si” decreases as distance “ds” from the source increases.

[si=1/(ds)2]

or

6 decibels “dB” decrease in si per 2(ds)

— from sound spreading hence the term

— all frequencies affected equally


reflection

— same as light if object is large w/ surface grain small relative to wavelength

— angle of wave hitting surface is equal to angle of reflected wave

–low vegetation high diffusion of wave

— water surface significant reflection(causes high amplitudes or missing frequencies)

— reflection not only occurs from two different media but also changes in the properties of the same media(air masses with different temp or humidity)