Source level reduction and sonar beam aiming in landing big brown bats (Eptesicus fuscus)

Jens C. Koblitz*, Peter Stilz, Wiebke Pflästerer, Mariana L. Melcón, Hans Ulrich Schnitzler

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Reduction of echolocation call source levels in bats has previously been studied using set-ups with one microphone. By using a 16 microphone array, sound pressure level (SPL) variations, possibly caused by the scanning movements of the bat, can be excluded and the sonar beam aiming can be studied. During the last two meters of approach flights to a landing platform in a large flight room, five big brown bats aimed sonar beams at the landing site and reduced the source level on average by 7 dB per halving of distance. Considerable variation was found among the five individuals in the amount of source level reduction ranging from 4 to 9 dB per halving of distance. These results are discussed with respect to automatic gain control and intensity compensation and the combination of the two effects. It is argued that the two effects together do not lead to a stable echo level at the cochlea. This excludes a tightly coupled closed loop feed back control system as an explanation for the observed reduction of signal SPL in landing big brown bats.

Original languageEnglish
Pages (from-to)3090-3099
Number of pages10
JournalJournal of the Acoustical Society of America
Issue number5
StatePublished - Nov 2011
Externally publishedYes


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