This is the microphone element recommended by Old Bird for recording night migrating thrushes, sparrows, and warblers. It is excellent for recording flight calls whose frequency is above 2 kHz, and note that the C1 capacitor is built in. The frequency response of the element can be seen on the Knowles Electronics EK series webpage. The element has a 12 dB per octave rolloff below 2 kHZ, thus greatly reducing rumble from wind, road, or aviation noise. High frequency sensitivity begins to drop off above 6 kHz but this is largely compensated for by the 6 dB gain in sensitivity from the dinner plate reflector.