Room safety device.

摘要

Strongroom protection device comprising a low-frequency system, an anti-masking ultrasound system and an alarm system. Low-frequency sounds are received by a microphone (1) and the sounds are amplified and converted into an electrical signal (2, 3) used to charge a capacitive circuit (4) which enables an alarm to be triggered if the average noise level exceeds a certain threshold. An ultrasound circuit (8, 9, 10) makes it possible to check that the microphone (1) is not masked. <IMAGE>