The unit is adequately protected from rain and wind and the heated preamplifier together with the
protective membrane coating of the microphone capsule provide stability of acoustic parameters over time
and allow you to make measurements over a wide range of environmental conditions.
The Delta OHM sound level meter preamplifier matched with the outdoor microphone unit is equipped with a
circuit for electrical calibration of the preamplifier – microphone chain, a technique that uses a charge
The frequency response of the unit in open field meets the specifications of class 1 according to IEC 61672
(and IEC60651) and was certified by I.N.RI.M. (Certificate of conformity No. 10-0126-02 of 04.29.2010).
The microphone unit HDWME must always be positioned vertically to allow the anti-rain to perform
its function and can be used both to detect the noise from the air and the ground. The Delta OHM sound
level meters perform spectral corrections to the measures to ensure tolerances in accordance with the
IEC61672 class 1 in every situation.
The easiness of disassembly and reassembly of the unit allows to perform periodic testing of the electroacoustic
characteristics the same way as a standard measurement microphone, using a standard calibrator
for ½” microphone.