New earplugs isolate specific noise

Measured by decibels, the crow of a rooster is somewhere between freeway traffic and the roar of a diesel freight train running at high speed. The one outside my bedroom window was more like the speeding freight train, except that it didn't go anywhere.

It's illegal to kill roosters in Key West, Fla., (not that I would, I'm just saying). And once they've found a good roost, they're very hard to dislodge, especially if they're in a neighbor's tree, whose limbs you can't hack off. After suffering through several nights punctuated by irregular intervals of rooster "song," as some ornithologists charitably describe it, there seemed only one solution to the noise problem that didn't entail violence: earplugs.

Earplugs are nothing more than tiny bits of foam, plastic or silicone with no moving parts, but they turn out to be amazingly complicated. Who knew that each human ear canal is as unique as a fingerprint? And that the bones of your skull also conduct sound, especially of low frequency, which is the frequency of most snoring? And that even deaf roosters crow?

Fortunately, the growing earplug industry is applying modern technology to the science of "sound management," attempting to isolate specific sounds to muffle instead of muffling everything equally. Companies are developing more effective ear protection not just for the sleepless but also for professionals like fighter pilots, rock musicians, miners and carpenters who have learned, some the hard way, that repeated exposure to loud noise can cause irreversible hearing loss. These people want ear protection that lets them hear co-workers' voices or warning signals but eliminates hazardous background noise.

New generations of earplugs and muffs attenuate noise more evenly across frequencies, so there's less distortion in the sound that gets through. Companies are also using new materials and designs to reduce the weight and bulk of ear protectors so users will keep them in for longer periods of time.

A common misconception about over-the-counter earplugs like the ones I tried is that they will render you artificially deaf, and you won't be able to hear someone yelling, "Fire!" or "That tree I've been sawing is about to fall on you!" In fact, earplugs can reduce sound only by about 20 to 30 decibels. A scale of sound intensity, decibels start at zero, the faintest sound an ear can hear, and rise to about 180, a rocket pad during blast-off. Normal conversation is about 60 decibels; a rock concert is about 115. Continual exposure to more than 85 decibels may cause hearing loss; pain starts at about 130.