Below a comparison between two recordings made simultaneously using two Marantz PMD660 recorders.
These are calls from a communal roosting, mainly consisting of about 200 Western Cattle Egret, with also the calls of European Robin, Blackbird and Magpie (At 1:15 a car passes on the back of the recorders).
No high pass filter was used. To match the recordings, +3 dB are applied to NT1a recording.
By listening with headphones, to start both tracks at the same time and then mute them alternately by pressing the button on the right side with the volume symbol.
Comments are welcome!