Have you ever wondered how far away bats and other animals can be and still be detected by your microphone? This is a question we get very frequently.
The simple answer is that there isn't a simple answer.
Microphones do not have a "range" in that they will capture any sound that reaches the element inside.
Atmospheric attenuation, the frequency of the sound, the direction the animal was facing, and a large number of other conditions all affect how far away a sound can be heard.
For acoustic microphones this translates to "if you can hear it, so can the microphone."
An owl calling from 800 meters away may be heard in a quiet forest where a mouse squeak may not be heard from 10m. Also humans have a great ability to filter out wind noise automatically, so you may be able to pick out a sound that is masked in a recording. On the other hand, there are times when you can see a sound in a spectrogram that you could not easily discern when listening in person.
When recording ultrasonic sounds such as bat echolocations with a microphone, a good rule of thumb is that most bat species can be detected at a distance of 30m with a likely maximum of 100m for a very loud, low frequency bat pointing directly at you in perfect conditions.
Wildlife Acoustics, Inc.
3 Mill and Main Place, Suite 210
Maynard, MA 01754-2657 USA
+1 (978) 369-5225
+1 (888) 733-0200