The purpose of this paper is to present a general theory and some techniques for analyzing, estimating, and displaying the characteristics of wave noise, random noise, and reflection signal, in a form convenient for designing and evaluating multiple seismometer arrays and filters. Modifications of the characteristics resulting from weathering and elevation variations, and modifications of the array responses resulting from variations in plant and seismometer spacing are discussed. Criteria for the design of arrays are presented along with a multiple seismometer nomogram based on a specific set of criteria.