Sound Testing Equipment
To perform sound testing in the field you will need a tachometer, sound meter, and RPM data sheets. The tachometer that most folks use is a vibrating reed tachometer available for about $25. The actual brand of the tach is Treysit but it is sold by both Briggs & Stratton and Tecumseh for testing small engines. You may also be able to order them through small engine repair shops.
As for sound meters, we've found that the cheap units from companies like Radio Shack are very inaccurate and not worth the effort or expense. For a more high-quality unit, we've been happy with the Quest sound meters. If you are looking for a good quality meter to use for educational purposes check out the Intercomp sound meter at: Intercomp Sound meter page
NOHVCC has found a Quest sound meter and tachometer package from Machovec. It may be the easiest and the least expensive source for the sound test equipment.
You can get RPM data sheets from the MIC Sound Manual or from the Motorcycle Industry Council's downloads page for the latest updates.