Noise doesn't sting your nostrils. Noise doesn't make you vomit. Noise doesn't bring tears to your eyes. Colorless, odorless and tasteless, noise seems harmless.

It isn't. Noise has social and physiological effects, and noise may be chipping away at your hearing. "It's a noisier world we live in," says Linda Vaughan, director of audiology practice management at the American Speech-Language-Hearing Association (ASHA).

The popularity of headphones and other technology has helped double the number of hearing loss cases. The country had 14.2 million cases in 1972 but now has more than 30 million, Ms. Vaughan says.

Ear-splitting noises aren't the sole hazard. Continuous exposure to sounds that measure more than 80 decibels (dB) can affect your ears, the ASHA says. Don't rely on pain as a test. It takes a sound of about 120 dB or greater to cause pain in your ears.

Gauging noise
You can gauge the safety of noise by using your voice. "If you have to raise your voice, in whatever kind of environment, it's too loud," Ms. Vaughan says.

How long you're exposed to the noise and your distance from it control the extent of hearing loss and how fast it shows up. A noise as loud as a gunshot (140 decibels) can cause instant, permanent hearing loss, which may start as a ringing or buzzing. Long exposure to noises from motorcycles, lawn mowers and the subway (90 to 100 decibels) can cause gradual hearing loss.

If you can't avoid damaging noises, protect your ears. "Earplugs aren't going to make it so that you can't hear anything," Ms. Vaughan says. Types of earplugs sold at drugstores can either lessen the sound or block it. You can also buy ear protectors that fit over the ears; this type of protection, worn by shooters and people who use loud machinery, cuts out even more noise. You may want to use both earplugs and ear protectors. Earphones also are available for air travelers; these devices block engine sound and wind noise.

If sounds seem distorted or muffled, if you have pain or ringing in your ears after exposure to noise, or if you find yourself asking people to repeat what they've said, it's time for a hearing test. You may also need to see an ear-nose-throat specialist. Hearing aids can remedy some types of hearing loss.

Common noise levels in decibels (dB)
Painful:
150 dB Rock music (peak)
140 dB Gunshot
130 dB Jackhammer
120 dB Car horn

Extremely loud:
110 dB Rock music
105 dB Helicopter
100 dB Motorcycle
95 dB Hair dryer
90 dB Lawn mower

Very loud:
80 dB Alarm clock
75 dB Busy traffic
70 dB Vacuum cleaner
60 dB Dishwasher

Moderate:
50 dB Moderate rain
40 dB Quiet room