All Kahlenberg sound signals are built to comply with The 1972 International Regulations for Preventing Collisions at Sea ('72 COLREGS), ANNEX III. This means they are capable of producing very high sound pressure levels.
Typical measurements are 123.5 dB (A) for the smallest horns in the range (the K-Series), 133 dB (A) for the D-0A and 138 dB (A) for the D1, all measured at 1m distance from the trumpet. These sound pressure levels will be considerably higher if sampled at closer range. Larger units also produce much higher volumes again.
Kahlenberg UK recommends that horns are installed and operated as per the recommendations in the COLREGS.
We have produced a safety guidance note which contains precautionary advice and links to further reading. Download Safety advice for Kahlenberg horns here