MED ASSO C IAT E S I NC. ANL- 940 - 1 U L TR ASO NI C M I CRO PH ONE AND AMPL I FIE R
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DOC-262 Rev 1.0 Copyright © 2012
MED Associates, Inc.
CHAPTER 1
Overview
The ANL-940-1 Ultrasonic Microphone and Amplifier accurately measures both the amplitude and
frequency of ultrasonic vocalizations emitted by laboratory rodents . This device is suitable for
measuring motivational behavior in drug addiction studies, mother-pup separation, isolation stress,
social interactions, sexual encounters, and many other paradigms. The instrument produces an analog
voltage output (BNC Connector) that is proportional to sound pressure level. The analog output can be
connected to third party data acquisition systems. (e.g. National Instruments)
Specifications
The frequency response of the ANL-940-1 is linear (+/- 4 dB) up to 100 kHz.
The analog output is +\- 14 Volts.
The ANL-940-1 microphone and preamplifier combination are calibrated to provide 1 volt peak output
into a high impedance load when excited with a 50 kHz ultrasound sine wave with a peak pressure level
of 1 Pa, or L
p
= +94 dB SPL (20 µPa = 0 dB). Peak levels were selected for ease of setting up associated A -
to-D converters, as the peak value could be easily related to the full -scale count of the converter. This
calibration is independent of distance from the sound source and reflects the actual sound pressure at
the face of the microphone.
The output impedance of the ANL-940-1 amplifier is 50 Ohms and must be considered when connecting
the unit to other measurement equipment.
Notes
1. The high impedance load assumed for calibration is high relative to 50 Ohms and the loading
effect of low impedances must be considered. For example, 500 Ohm load has an error of less
than 1 dB, while a 10000 Ohm load has an error of less than 0.05 dB.
2. If the A-to-D has 50 Ohm load, the sensitivity is reduced to 0.5 V peak due to the drop across the
ANL-940-1 internal impedance. Many instruments have a fixed 50 Ohm input impedance, so the
input impedance of your recording hardware should be determined if your goal is to make
quantitative measurements of vocalization amplitudes (in dB).
Requirements
- Third party data collection hardware and software
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