These telephone protection hoods
are an excellent aid to eliminate extraneous noise and improve audibility in noisy surroundings where open telephones have to
be installed for economic reasons. The special shape of the hood and its inner lining of sound-absorbing material optimally
reduces noise in the area of the telephone. Eavesdropping is also made difficult. The best acoustic effect is achieved when the
protection hood is mounted with its back facing the noise source or loudest noise source. The hood is made of sheet metal
and lined on the inside with sound absorbing mineral fibre boards behind a perforated plate cover.