The most common type of bat detector used today is known as a heterodyne detector. The human ear hears the difference between the frequency of the bat call and the frequency setting on the detector.
For example: Typically a Common Pipistrelle bat will produce a call at a frequency of 45kHz (or thereabouts). To obtain an accurate call the detector needs to be set close to this value. If it is set at 48KHz then the difference is 3KHz which falls within the human hearing range. If the detector is set too far away then the call will not sound clear or will be inaudible.
Hetrodyne bat detectors are fantastic for beginners and keen hobbyists alike. Their simple to use operation and proven reliability make them the go to choice for anyone keen on finding out more about the nocturnal world of bats. By converting the ultrasonic bat call into a sound detectable by the human ear these detectors are excellent for species level identification.
The Bat detective field guide and CD is an additional way of learning about the different species of bat found in the UK and how to detect them from their calls and is highly recommened alongside any bat detector purchase.
Ecologist Oliver Reville recommends the Magenta 4 or 5 bat detectors; “These simple to use but highly effective detectors give users everything they could want from an enthusiasts detector. It offers a great starting point into the world of bats with easy to use controls and fantastic sound reproduction”