Bat sound analysis


With the time expansion technique the calls are recorded, and the file is displayed for instance 10 times slower. The time-expanded sound is analysed in a computer program and the diagram (sonogram, spectrogram) can be stored as a picture-file.

The spectrograms (frequency curves) below are recorded with a Petterson D240X bat detector,  saved in a digital Roland R-05 recorder and analysed with the BatScan 9 computer software.

The spectrogram shows how the frequency changes over time. Yellow and red indicate high sound intensity.



Calls used for Echolocation

Brown long-eared bat (Plecotus auritus)

Barbastelle (Barbastella barbastellus)

The barbastelle typically use a double ecolacation call consisting of a loud call at 36 kHz to 28 kHz and a quieter call at 44 kHz to 29 kHz.

Barbastelle. Sometimes the quieter call type is omitted. Recordet at a woodland edge.

Whiskered bat/ Brandt's bat

It is nearly impossible to discriminate between Brandts bat and whiskered bat. Note the variations between calls