Part I of this monograph gives a brief description of the causes and some of the effects of some booms produced by supersonic aircraft. The results of measurements made during a demonstration of sonic booms have been used to show that studio roofs having an average insulation of 70 dB are probably adequate protection against sonic booms of intensities likely to be accepted in urban areas. In some circumstances insulation provided against other aircraft noises may be adequate to exlcude sonic booms and in Part II the actual levels and spectra of the noise from subsonic aircraft (including helicopters), as well as the distribution of noise levels around a major airport are considered in order to reach a specification for the sound insulation of roofs to exclude such noise.