Norsonic Nor1212, Instruction Manual

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Norsonic Nor1212
User Guide
3
1 Introduction
The Outdoor microphone kit Nor1212 allows the standard measurement
microphone Nor1225 with preamplifier Nor1201 or Nor1206 to be used
as an all-weather microphone for semi-permanent applications. The
Outdoor Kit protects the microphone from rain and snow, dust and
insects.
Further, the Outdoor kit improves the measurement accuracy by reducing
the wind noise and by changing the directional response of the
microphone capsule to suit vertical mounting.
The Outdoor Kit allows the Nor1225 microphone to retain its Class 1
specifications according to IEC6051 and IEC61672-1 when the weather
protection system is in place.
The acoustic sensitivity for free-field measurement microphones, like
Nor1225, is optimised for sound reaching the microphone along the axis
of symmetry. When mounted for outdoor measurements the microphone
is normally mounted with the diaphragm pointing upwards. The
microphone response will therefore be at its best for sound from above.
Even for aircraft noise monitoring, the sound will seldom approach the
microphone just from this direction. The outdoor kit has therefore been
designed to change the directional characteristics of the microphone to
improve the accuracy in other directions. The result is a microphone with
a response almost symmetrical around the horizontal plane and with a flat
random incidence response.
The Outdoor Kit allows the microphone to be calibrated with a normal
sound calibrator without the need for extra accessories. Access to the
microphone is gained by dismounting the upper part of the kit.
The outdoor kit is made of an electrical insulating material. The
microphone body will be fully insulated from the mounting mast thereby
reducing pick-up of electrical hum and noise.