Recent advances in computer technology have opened new opportunities for recording and monitoring of animal sounds. High quality PCI-bus soundcards with up to 8 channels, initially designed for music production, are now available at a reasonable price. Such soundcards installed in a Windows-PC with a fast hard drive are the basis for a versatile sound capturing system. This software is able to manage up to four soundcards installed in one PC. Up to 8 channels, each sampling at up to 48 kHz, can be monitored simultaneously. For low frequency or ultrasound applications not supported by soundcards, special data acquisition boards could be used. Each channel can be triggered separately by different trigger events. A trigger event is usually the exceeding of a certain energy threshold within a defined frequency band. This prevents triggering caused by undesired disturbance signals outside the frequency range of the animal vocalisations. Alternatively, trigger events could be keystrokes or joystick button hits. Once a trigger event has occurred, the assigned channel(s) will be written into numbered WAV-files onto the hard drive as long as the trigger event is active. In order to capture sounds preceding the trigger event, a pre-trigger duration can be specified. Additionally a hold-time is implemented in order to prevent cutting up of related sound elements. The adapted Avisoft-SASLab sound analysis software and the LOG-file output support quick navigation through the captured sound files.
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