The L400 is an ultrasound loudspeaker with a built-in amplifier that can be connected to any recording device capable of playing ultrasonic signals. The speaker is most effective when used with recording/playback devices which are purposely designed for ultrasound signals, such as bat detectors. However, a computer with a high performance sound card (192 kHz sampling rate) may also be used and most will play sounds of up to 85-90 kHz. (Please note that this will only work if sound files have a sampling rate which is supported by the sound card. If the file is a time-expanded or high-speed recording, re-sampling of the file to match the rate of the sound card will be required in order for it to be played correctly).
The L400 is a great teaching aid giving students the ability to listen to recorded bat calls from the loudspeaker using their bat detectors.
The speaker can also be used effectively as an acoustic lure when detecting in the field.
Please note, however, that a license is always required to use a lure for bats.