1. Statham Radio
This microphone is small, and designed to be hardy. The microphone is ¼ inch (6.35 mm) in diameter, and is not encased in a pre-amplifier capsule. This allows it to be used in spaces with limited room, such a small tiger stall that is approximately 1 meter by 2.5 meters. This microphone can record from 1.5 Hz to 22 kHz (+/- 3 dB).
Temperature: (00 C to 41.10 C)
Signal to noise ratio 66.1 dB/(Hz)1/2 @ 1 Pascal
Sensitivity is 19.6 mV/Pa.
The microphone is based on, and is comparable to, the Bruel and Kjaer 4133. An Audio Technica windscreen, with 10 – 20 dB attenuation, external diameter of 7 mm, and weight of 1.5 g, is used with the microphone, and is comparable to the specifications of a Bruel and Kjaer UA 0459 windscreen.
Calibration of the microphones is performed at Statham Radio every 6 months, using a Bruel and Kjaer 2608 measurement amplifier, a Bruel and Kjaer 4231 calibrator, an Audio Precision System 1, and an Electrovoice 1821 compression driver for measurements below 40 Hz. All Statham Radio calibration devices are certified by the manufacturers annually.
Cost: $300 a unit
2. Chaparral Model 2
The Chaparral is a low frequency mic, flat to within 3dB from 0.1 Hz to 100 Hz.
Standard sensitivity 0.2 volts/microbar (high) to 0.04 volts/microbar (low).
Maximum output 18 volts peak to peak
Output impedance 200 ohms in series with 330 mfd.
Temperature –40 to +150 degrees F
Size: 8" high, 7 1/4 diameter
Weight: 4 lbs
Calibration by Chaparral Physics
Because of the capability to record directly to the portable computer using the PCMCIA card, this microphone is an extremely accurate and handy tool for recording infrasound in the field.
3. USRD F42D Reciprocal transducer (hydrophone)
The USRD hydrophone is used for recording a range of vocalizations, from 100 Hz to 150 kHz. Weight: 4.5 lbs
Maximum depth: 3500 meters
Temperature range: 0 to 30 degrees c
Directivity: Omnidirectional in the horizontal (xy) plane and omnidirectional within +/-2dB in the vertical (xz) plane.
Calibrated by USRD
For frequencies below 100 Hz Statham radio microphones can be placed in a hydrophone casing and recalibrated.
Endevco model 22
Amplitude response +/- 1dB .5 Hz to 10 kHz
Charge sensitivity typical .40 pC/g, minimum .30 pC/g
Amplitude linearity to 500 g 1%
Temperature 173 to +149 degrees c
Sinusoidal vibration limit 2500 g pk
Weight .14 gm
Calibrated by Endevc
5. Field Calibration
Calibration of the recording system in the field to insure accurate levels during recording, analysis, and playback is performed using a Bruel and Kjaer 4226 multifunction acoustic calibrator. The 4226 generates accurate and stable signals ranging from 31.5 Hz to 16 kHz in octave steps. The 4226 dimensions are 265 mm long, 125 mm wide, and 62 mm high. The unit weighs 1.5 kg. The 4226 is certified by the manufacturer annually.