Sep 20, 2012

Bat Recordings - with the Anabat SD2 - Ultrasonic Echolocation Detector

Bat Recordings - with the Anabat SD2 - Ultrasonic Echolocation Detector Bat field recordings from a recent trip to the North GA mountains. This sound clip was captured using the Anabat SD2 - Bat Detector - high microphone. This device allows you to monitor the ultrasonic echolocation calls of bats for species identification and activity measurement. The particular species of bat in this recording are the Indiana Bat. The typical hearing range of this bat is between 20hz - 150Khz. They locate their prey by means of echolocation. They will produce a very, loud short sound and assess the echo when it bounces back. The type of insect and how big it is can be determined by the quality of the echo and time it takes for the echo to rebound. They also use two frequency types; constant frequency (CF) and frequency modulated (FM) calls that descend in pitch. Each type reveals different information for the bat. The CF is used to detect an object, and the FM is used to provide information regarding the nature of the object and its distance. The pulses of sound produced by the bat last only a few thousandths of a second with silences between the calls that give time to listen for the information coming back in the form of a echo. I was amazed at how complex some of these echolocation patterns looked on a sonogram and was even more blown away by how they sounded. This file was outputted from the Anabat software application which takes the bat calls and converts them to wave files. The Anabat software application also converted the calls to a audible human hearing range (20hz-20khz) as most of the bats calls went up into the 150khz range.

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