R it has been suggested that desirable modifications of objectionable sonic boom pressure signatures may be accomplished by the addition of mass or energy or by electro-aerodynamic means. The possibility of successfully utilizing any of these schemes is a matter of much current controversy." It is the purpose of this Note to present simple analytical techniques with which proposals involving mass or energy addition may be evaluated and to infer some preliminary results concerning their feasibility. The objective of the proposed mass or energy addition schemes is to create a "phantom" boundary which will favorably alter the effective area distribution of a given airplane. Such favorable alterations may be designed to produce either plateau (AeaX) or finite rise time (AeaX*) pressure signatures. The effective area variation required of the addition scheme is, therefore, the difference in effective areas between the phantom and actual bodies