If the initial values are unknown, LBF can measure the noise levels of the sound source. These are then indicated as sound power levels or sound pressure levels, and form the basis for the evaluation of the sound propagation. In order to comply with maximum allowed values, the necessary noise protection measures are defined as: output level - required maximum allowed level = necessary attenuation! Silencers are measured according to DIN standards in our acoustic lab: transmission room equipped with a wall of speakers – duct with silencers – reverberation room!