Outdoor Microphone System - Page 6
G.R.A.S. Sound & Vibration
Fig. 1.2 Outdoor Microphone System. Types, reference
directions and applications
1.1
Available Types and Applications
There are two types of the Outdoor Microphone System, these are Type 41AM and Type 41CN.
Each has its own measurement reference direction and application, i.e.:
Type 41AM
Measurement reference direction - vertical (along axis of symmetry)
Angle of incidence - 0°
Application - monitoring airport noise
Type 41CN
Measurement reference direction - horizontal (perpendicular to axis of symmetry)
Angle of incidence - 90°
Application - monitoring community noise
See also Fig. 1.2.
Both types are almost physically identical; differing only in the type of the microphone cartridge
and rain-protection cap used. Type 41AM uses Microphone Cartridge Type 41AS and Type
41CN uses Microphone Cartridge Type 40AS.
Reference Direction
0° incidence (airport noise)
Type 41AM
Reference Direction
90° incidence (community noise)
Type 41CN