A Digital-Readout Sound Level Meter with Automatic Range Switching

Abstract

One of the main problems confronting sound engineers who must make a noise survey armed only with a sound level meter is the determination of the effective level of a noise that fluctuates through a wide range. If the range of variation is more than 15 dB, or if changes occur very rapidly, it is nearly impossible to arrive at a reasonable average figure. Therefore, a sound level meter was developed that not only automatically switches ranges according to the input level, but also provides a digital readout for on-line or off-line linkage to a computer. Problems of integration time and frequency of readout are discussed in terms of present knowledge concerning what constitutes the “effective level” of time-varying noise.