The noise spectra in present military aircraft are reviewed, describing the characteristic sources. Objectives for noise control based upon communications, aural damage risk, and comfort are proposed. The probable maximum increases in noise exposure are described, and the prospects for control in future aircraft and space vehicles are discussed. Requirements for personal protection are deduced. Latest methods of evaluation of speech projection and reception systems are based both or physical measurements and intelligibility testing. Highly efficient articulation testing is based upon most difficult consonant sounds and upon simulated flight command sentences. Results permit rating of systems in terms of noise tolerance as a function of speaking effort.