THE advantages which arise from the directness and speed of aircraft, and the high record for safety held by Air Lines like Imperial Airways, contribute to the increasing popularity of air travel. With many persons, however, the chief deterrent at present is understood to be the discomfort caused by the noise experienced, and there is no doubt that there are civil aircraft in use to‐day which are excessively noisy. Consequently attention has been directed recently in this and in other countries to suppressing the considerable noise to which passengers in aircraft cabins are usually subjected. The experiments are not yet completed, and it is not possible yet to answer all the questions that may arise. It is thought, however, that the following account of the trend of present results, as judged from recent work in the light of the writer's own experience, may be helpful in indicating the principles involved.