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ANNEX VIIMINIMUM REQUIREMENTS FOR ACOUSTIC SIGNS

1. Intrinsic features

1.1.Acoustic signals must:

(a)

have a sound level which is considerably higher than the level of ambient noise, so that it is audible without being excessive or painful;

(b)

be easily recognizable, particularly in terms of pulse length and the interval between pulses or groups of pulses, and be clearly distinct from any other acoustic signal and ambient noises.

1.2.If a device can emit an acoustic signal at variable and constant frequencies, the variable frequency should be used to indicate a higher level of danger or a more urgent need for the requested/imposed intervention or action in relation to the stable frequency.

2. Code

The signal for evacuation must be continuous.