Ultrasound Microphones
for field recorders and USB audio interfaces that provide P48 Phantom Power
Avisoft Bioacoustics offers three phantom-powered ultrasound microphone models that are compatible with common field recorders (such as the Tascam Portacapture X8 and SoundDevices MixPre-3) and USB audio interfaces that provide a high sample rate of 192 kHz and the required 48V phantom power:
| Microphone model |
Knowles FG | MEMS | CM16/CMPA-P48 | ||
| Part # | 40002 | 40110 | 40012 | ||
| Microphone principle | pre-polarized condenser (electret) |
MEMS (Micro-Electro-Mechanical Systems) | externally polarized condenser (200V) | ||
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| Relative flatness of the frequency response | poor (see frequency response) |
medium (see frequency response and frequency response compensated using Avisoft RECORDER or SASLab custom filter .mems.flf) |
good (see frequency response) |
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| Approximate self-noise level 30 … 50 kHz | 41 dB | 28 dB | 18 dB | ||
| Approximate sensitivity | 500 mV/Pa | 500 mV/Pa | 500 mV/Pa | ||
| Phantom power requirements | 48V, 10mA | 48V, 10mA | 48V, 10mA |
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| Durability of the diaphragm | good | good | very good | ||
| Reliability in high-humidity environments | good | good | good | ||
| Total size [mm] | 20 x 20 x 47 | 21 x 21 x 42 | 36 x 36 x 120 | ||
| Weight | 40g | 34g | 155g (including CMPA) |
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Note that the frequency responses of some field recorders (certainly at the 192 kHz sample rate) are not optimal for recording ultrasounds above about 60 to 70 kHz. The aliasing performance (rejection of signal components at frequencies above the nyquist frequency) is not satisfying and might reduce the effectively usable bandwidth.
For recording higher ultrasounds, it is therefore recommended to use a recording system that supports sample rates higher than 192 kHz and more appropriate frequency responses (for instance one of the UltraSoundGate devices).