This noise was reduced somewhat by choosing proper rotor and stator blade numbers and spacing and by using engines of the single-mixed-jet type. The introduction of the turbofan engine, with its lower jet velocity, temporarily alleviated the jet noise problem but increased the high-frequency turbomachinery noise, which became a severe problem on landing approach as well as on take-off. Take-off noise restrictions were imposed by some airport managements, and nearly all first-generation turbojet-powered transports were equipped with jet noise suppressors at a significant cost in weight, thrust, and fuel consumption. Accordingly, much effort was devoted to developing jet noise suppressors, with some modest success.
It was recognized at the time that the noise levels produced by turbojet powered aircraft would be unacceptable to persons living under the take-off pattern of major airports. Though long of concern to neighbors of major airports, aircraft noise first became a major problem with the introduction of turbojet-powered commercial aircraft (Tupolev 104, Boeing 707, Dehavilland Comet) in the late 1950s. Tupolev 154M noise asesment (Анализ шумовых характеристик самолёта Ту-154М)Ĭontents 1 The Noise Problem 2 Effects of NoiseĢ.4 Noise Influence on Health 3 Noise Sourcesģ.2 Turbomachinery Noise 4 Noise Measurement and RulesĤ.2 Effective Perceived Noise Level (EPNL) 5 Noise CertificationĦ.2.2 Landing Approach Noise Claculation 7 Noise Suppression
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