I used a parabolic mic (with AOM5024 capsules) on a ZOOM F3 recorder. The bird was distant, the call was faint, and in theory below the frequency range of the parabola. But it still recorded.
Anyone have suggestions of mics that are known to be good at recording such low frequencies from 10-20 meters distance?
Basically most mics will do the job. I think Bare-necked Umbrellabird has a call above 500Hz, and most mics work below this level.
Things to look for in the mic spec are as follows;
1/ Frequency response - e.g. a figure something like 50- 20,000Hz. As I say if the frequency response starts at below 500Hz it should be OK for your purposes.
2/ Frequency response chart - basically this is a graph showing a line for the response for any given frequency. This should for most mics be a fairly flat line. What you don’t want is any drop off at low frequencies, otherwise the mic will be poor at recording low frequency noises.
3/ Sensitivity figure. These figures are confusing and sometime presented as mV/Pa and sometimes as
dB re 1 V/Pa. With mV/Pa the larger the figure the more sensitive the mic is, so the more it will pick up quiet noise. For dB re 1 V/Pa the figure will be minus and in this case -23 is a lot more sensitive than say -34.
Unfortunately shotgun mics are poor at filtering out off axis low frequency unwanted noise - they are more directional at higher frequencies. You therefore run the risk than unwanted noise may drown out the umbrellabird call, particularly if the call is quiet, and environmental noise significant.
Having a high sensitivity mic has pros and cons. It will pick up quieter sounds, but at low frequencies as it will be none directional it will pick up everything, including unwanted noise.
3D Pan mentions recording with a parabola, but his recordings can only have worked because the sound reached the mic direct, rather than being reflected and amplified by the dish. This is because physics dictates that the wave length must fit within the dish for there to be any amplification of the sound. The gain is then relational to the frequency, so for moderately low frequencies you get a small amount of gain, but for high frequencies you get lots of gain.
Given the poor directional behaviour of shotguns at low frequency, you could just use an omni or cardiodal mic, but then these are less suited to recording other birds.
I would therefore stick to a shotgun, but look through the specs and choose one with reasonable high sensitivity, no drop off in the frequency response at low frequencies and a frequency range starting at or below 100Hz. The trickiest bit is the sensitivity - I think the ME67 (no longer available) had a sensitivity of 50mV/pa or -28dB re 1V/Pa. This mic was always considered a good shotgun for bird recording, but I think mics now with this type of performance are not that common, so you have limited choice in very sensitive shotguns.
