Bats louder than jet plane Bats scream louder than a rock concert or a jet plane. Fortunately, they do this at a frequency which cannot be perceived by the human ear.
They produce ultrasonic sound for orientation in the dark and to find prey. The screech of a bat can reach up to 140 decibels …exceeding a rock concert by 20 decibels and the human pain threshold by 15 decibels. Bats are among the loudest animals – only we cannot hear them as the human audible range is too limited. In Panama scientists recorded the sounds of eleven species of bats. They placed microphones in their hunting areas. The highest sound level was generated by the bulldog or fisherman bat, the loudest flying animal in the world with a record of up to 140 decibels.
The nocturnal hunters find their prey by means of echolocation: They generate ultrasonic sounds and listen for the echo reflected by their prey. Doing so they must be the louder the higher the frequency of their sound is, because highfrequency sounds die away very quickly in the distance. The prey will remain undetected. The louder they scream, the wider their reach and their chance for prey. The loudest screamers, however, did not have the widest range. The bulldog bat could only locate prey at a maximum distance of nine meters. The species of sac-winged or sheath-tailed bats had a wider range: Their scream is quieter but at a lower frequency and consequently not absorbed by the atmosphere. They reached prey at a distance of 17 metres. Incidentally, bats close their ears when they scream. This protects them from their own screeching but not from the screams of their conspecifics.
|die away||abebben, verhallen, ausklingen|
|exceed||überschreiten, größer sein als|
|nocturnal||nächtlich, ... der Nacht|
|pain threshold||Schmerzgrenze, Schmerzschwelle|
|quiet, quieter||ruhig, leise|
|range||Reichweite, Bereich, Reihe|
Autor: P. Zillmer
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