A simple logarator (logarithmic compressor)

A circuit comprising rectifiers, diodes and incandescent lamps as nonlinear resistors, and linear resistors to produce a dc output proportional to the largest of one or more ac inputs has been devised. It is capable of a linear range of more than 25 db with 0.5 db accuracy. Applications include plotting of response curves in decibels and measuring reverberation time. Two or more spaced microphones may be used under reverberant conditions to minimize effects of standing wave nulls or to simulate binaural hearing.