The Chairman, in opening the meeting, said that after all the comment in the Press in the last few days concerning the noise of helicopters flying over London and in view of the possibility of further comment in the immediate future because of the existence now of a heliport in London, it was opportune that the Association should be having a lecture this evening on “Helicopter Noise Suppression” from one of its members, Mr H B Irving, who was a leading authority on the subject