Another prime example why the tascam dr40 is complete useless as a field recorder. Picked up this interference somewhere literally in a field in the middle of nowhere. Do not buy.
A recording of a faucet being turned on and the water volume slowly increased, then decreased to give a full range. Recorded using a zoom h4n field recorder.
Recorded with a zoom device , time of day- evening, a field about 300 meter from highway. Sometime a random car on a gravel root pass by. Crickets are chirping. .