27jun11 How to copy ultrasound subliminal voices and play them back: The SM2 bat detectors are rapidly becoming the most popular units for passive recording in the UK and Europe. With high quality full spectrum recordings, waterproofing for field use, and at signicantly less money than other brands, they are the obvious choice for ecologists and universities. The 384kHz version records calls up to 170kHz, making it ideal for Lesser Horseshoes, although it is possible to identify likely Lesser Horsehoe activity even on the 192 version which records up to 96kHz. Whilst the 384 version is necessary for full analysis of high end calls, the 192 version carries the advantage of 2 channels, which effectively gives you two detectors in one. With the use of an extension cable up to 100m, this one monitor can simultaneously record at height and at ground level. see: http://www.wildcareshop.com/Products_Detail.php?ProductID=1566 there are cheaper ways