New York, American Telephone and Telegraph Company, 1951. 8vo. In the original printed blue wrappers. In "The Bell System Technical Journal", Volume XXX, Number 4, part II, 1951. Entire issue offered. Light miscolouring to spine. A fine fine and clean copy. Pp. 1145-1173. [Entire issue: Pp. 1041-1254.].
First appearance of Wallace on how to preproduce magnetically recorded signals.
"In early studies R. L. Wallace devised conference-room systems for stereo reproduction, having small loudspeakers placed in chair backs. Wallace also demonstrated that externalization of sound images could be obtained from stereo earphones that were carefully compensated for ear-canal response". (Millman, A History of Engineering & Science in the Bell System).