See the difference.
The SMM-U2 ultrasonic microphone is significantly quieter than the previous generation SMM-U1, and competitor's microphones.
Below are two bat recordings created simultaneously with an SMM-U1 ultrasonic microphone and the next-generation SMM-U2 ultrasonic microphone. The SMM-U2 microphone's superior signal to noise ratio results in recording fainter bats and bat calls at greater distances. In addition, more echolocation pulses are recorded, which allows more accurate identification.
SMM-U1 Ultrasonic Microphone:
SMM-U2 Ultrasonic Microphone:
Recorded by Paul Ullrich on May 31, 2018 in Maynard MA, USA.