Our Sound Level Meter (SLM-BTA, $209) offers lots of possibilities for the kind of investigations that students really get into. Here are some ideas:

• Some hair dryers are really noisy, and the noise source is right next to your ear. This inspired us to do a little checking. We tested five hair dryers, recording the sound level with the dryer about 2 cm from our Sound Level Meter (about the closest distance the hair dryer gets to your ear). The noisiest hair dryer read around 101 decibels and the quietest read near 90 dB.
• We went to a “Battle of the Bands” concert a few months ago, and recorded sound levels of 104 to 110 dB during performances.
• The October issue of Physics Today had a small article on sound levels in aerobics and other exercise classes in fitness clubs. The authors report levels as high as 120 decibels.
• Other noise situations that might be interesting for student investigations include headsets, pep rallies, and traffic.

It is easy to find OSHA noise standards on the internet for comparison with measured levels.