A Community Noise Monitor
Bill D. Cook, Lawrence I. Farley · The Journal of the Acoustical Society of America · 1974
A low-cost device has been built for obtaining a histogram of community noise levels. Signals from a sound level meter or tape recorder are appropriately rectified and level sensed by ten comparators. From the output of the comparators and a logic network, currents are furnished to a bank of electrolytic storage cells, known as E-cells. The charge imposed on a cell is a measure of the time that the sound level is within some preestablished bounds. After a period of sampling, the E-cells are removed from the device and the charge read by a commercial instrument.