Likely, you have encountered applications where the measurement of sound-pressure level does not demand rigorous, scientific precision. Possible examples include showing students how to make sound measurements, assessing the noise level in a third-grade classroom or monitoring your lawnmower’s sonic output during operation. Such situations call for a sound level meter (SLM) that is rugged, easy to operate, portable, and preferably inexpensive.

We have found that Radio Shack’s Digital Sound level Meter (catalog number: 33-2055) meets these criteria. At under $60, this SLM is priced about two orders of magnitude below the sophisticated SLMs found in the laboratory. The unit is small and fits comfortably in the palm of your hand. It weighs about 165 grams (less than 6 ounces), which includes the 9-volt battery. Two types of readout are provided. The digital display is very easy to read. Additionally, the bar graph is useful when describing how sound levels fluctuate over time. The meter’s operating range is 50–126 dB SPL. This range and the 1-dB resolution are adequate for most applications. The meter is equipped with ‘A’ and ‘C’ frequency weighting functions. The ‘Fast’ or ‘Slow’ time weighting functions permit the bargraph to be updated of at intervals of 0.2 or 0.5 seconds, respectively.