Norsonic nor1218, Instruction Manual

6

Chapter 4

Technical description

be used for connection to the sound level meter in-
strument. An adaptor for mounting the outdoor micro-
phone on a tripod is included.

The base is made of black polyacetal (POM). The 

material is durable and insulating, thus preventing 
electric noise from ground loops through the mast.

Drops of water from rain are kept away from the mi-

crophone diaphragm by the combined act of the tubu-
lar windscreen, the rain hood and the dust mesh. The 
upper part of the microphone cartridge is air- and wa-
ter tight, and the backside is vented to the air through 
the preamplifier. 

The Ingress Protection Category for the assembled 

microphone is IP55 according to IEC 60529.

Consider the assembly of microphone cartridge 

and preamplifier as a single unit when operated in the 
field. If disassembled in the field, the performance may 
be reduced due to contamination from dust and hu-
midity.

When Nor1218 substitutes a normal measurement 

microphone on a sound level meter, a correction of the 
frequency response is needed to retain the class of 
accuracy for the sound level meter, see Specifications. 
Based on the correction, the reference direction may 
be selected to be either horizontal or vertical. Horizon-
tal reference direction is usually selected for sound 
approaching the microphone mainly along a horizon-
tal axis like noise from industry or vehicles. A vertical 
reference axis is usually used for measuring the noise 
from aircraft.

The sound level meters Nor131 and Nor139 have 

a correction network where the reference axis for the 
outdoor microphone Nor1218 may be selected to be 
horizontal or vertical.

See separate description in this manual on how to 

configure the Nor131 or Nor139, Chapter 5.

Rain hood

Microphone 

cartridge

Dust mesh

Wind screen