VLF stands for Very Low Frequency & the receiver range is 0hz - 22khz........What can you hear ?........Sferics (Lightning), Chirps, Dawn Chorus Whistlers What do i need to hear these sounds ?........Just a simple pre-amp & an antenna of about 1-2 Metres long Do a search on Google for "VLF Schematic" where you'll find lots of information & schematics........A link to a schematic of my receiver is available further down the page