anechoic room - a room in which internal sound reflections are reduced to an ineffective value by extremely high sound absorption, eg by using glass-fibre wedges
The warning device shall be tested in a sufficiently silent and open area (1) (ambient noise and wind noise at least 10 db (a) below the noise being measured) or in an anechoic chamber; the microphone of the measuring instrument shall be located in the direction in which the subjective sound level is at a maximum and 2 m from the front surface of the device, the microphone and the device being positioned at a height of 1.20 m above ground level.
