More on Shop Noise

Q:

David Heim’s article (FWW #189) on shop noise gives figures on noise levels for various tools and noise reduction by several types of earplugs and muffs. How do I determine the noise level of two tools running together? And what is the noise reduction of earplugs and muffs worn together?

John Rennie, Knoxville, TN

A:

According to Les Blomberg, director of the Noise Pollution Clearinghouse, if one machine is at least 10 decibels louder, or twice as loud as another (decibels are on an exponential scale), then the noisier machine sets the resulting level. If the machines are about equally loud, then their combined sound level is a bit greater than the louder one. For example, two machines that each generate roughly 90 db. of sound produce 93 db. together, the equivalent of a 30% increase.

Bear in mind that the louder the sound, the less time you safely can be exposed to it without protection. As for combining hearing protectors, research indicates that the practice would serve little or no purpose for woodworkers. Earplugs with muffs, for instance, are only marginally superior to plugs or muffs alone.

Photo: Steve Scott

Fine Woodworking Recommended Products

Stanley Powerlock 16-ft. tape measure

With its smooth lock, tough case, compact size, and excellent accuracy, this Stanley tape is perfect for workshop use.

Buy at Amazon

Veritas Micro-Adjust Wheel Marking Gauge

The adjuster runs through the beam from a small knob at the back end right to the cutting wheel, which moves in and out as you turn the knob. This arrangement works well but makes adjustments a two-handed operation, requiring a little more effort.

Buy at Lee Valley

Blackwing Pencils

If you've listened to Shop Talk Live, you've heard them talk more about these pencils than you could possibly imagine.

Buy at Amazon