Silenced Test Beds: Experiments that Have Been Carried Out in Various Countries to Reduce Noise

TERRIFIC noise is one of the most undesirable features of aeronautical engineering. For the aeroplane passenger the introduction of the sound insulated cabin surmounted the difficulties some years ago, and the gradual perfection of the acoustic treatment has kept pace with the increased noise of faster airscrews and larger engines. Attention is nowadays given to ground test beds where the noise often reaches a painful intensity, and power plant manufacturers are finding it necessary to provide themselves with silenced test equipment.