Energy-Decay-Rate Timer

Abstract

A device is described for the measurement and automatic printout of the decay rate of reverberant sound energy or the damped vibration of structures. The design provides for a choice of decay ranges from 10 to 100 dB (in 10-dB steps), the point in the decay at which the timing starts (in 2-dB steps), and the number (up to 99) of decays to be measured and accumulated before printing. The signal to be measured is rectified and smoothed by a variable RC network, and then actuates a Schmidt trigger that starts and stops an electronic counter. The maximum measurable decay rate is better than 2000 dB/sec.