Old Bird 21c details
Includes a manually switchable high pass filter for use in situations with extreme road, aviation, or surf noise, etc. This filter essential takes out low frequency sound below 1 kHz.
A series of five short tones are produced when the 21c is first powered and thereafter once every hour. The tone is detectable by Old Bird flight call detectors "Tseep" and "Thrush" and is useful for verifying operation of the microphone, documenting changes in ambient noise levels, and gauging microphone sensitivity over time.
The 21c is especially sensitive to sounds in the 2 kHz to 10 kHz frequency range.
Instructions for setting up the Old Bird 21c microphone