What is a decibel?
The soft whisper of a grandchild sharing a secret, the loud blare of a fire truck's siren as it enters the intersection, the soothing melody of your favorite song on the radio. How do we measure the intensity of the sounds they make? Behold the humble decibel, a logarithmic way of describing a ratio between things like power, sound pressure and voltage.
Decibels measure sound intensity
Sound is energy that travels in waves and is measured in frequency and amplitude. Frequency, reported in Hertz (Hz), measures the number of sound vibrations in one second. Amplitude, reported on the decibel (dB) scale, measures its pressure or forcefulness. The more amplitude a sound has, the louder it is.
The logarithmic decibel scale measures differently than a linear scale. For example, every increase of 10 dB on the decibel scale is equal to a 10-fold increase in sound pressure level (SPL). Near silence is expressed as 0 dB but a sound measured at 10 dB is actually 10 times louder. If a sound is 20 dB, that's 100 times louder than near silence.
Decibels and hearing loss
Decibels might be just another measuring stick if it weren’t for the damaging effects loud noise inflicts on our hearing. Whether it’s a one-time exposure to a loud explosion or daily exposure to an excessively noisy workplace or hobby, our hearing suffers the consequences. This type of hearing loss is known as noise-induced hearing loss (NIHL).
The National Institute on Deafness and Other Communication Disorders (NIDCD) says everyone is susceptible to hearing damage as a result of noise exposure. They estimate approximately 15 percent of Americans between the ages of 20 and 69 have hearing loss that may have been caused by exposure to loud noise at work or through leisure activities. Results from a 2010 survey conducted by the Centers for Disease Control and Prevention (CDC) reveal as many as 16 percent of teens (age 12-19) report some hearing loss that may have been caused by exposure to loud noise.
Scientists have studied the effects of NIHL and, based on the levels of sounds in our environment, established recommendations for safe listening. How loud is too loud? The louder the sound, the shorter the amount of time it takes to damage hearing. Repeated or prolonged (more than 8 hours a day) exposure to noise louder than 85 dB can permanently damage hearing. And, in case you’re wondering what types of sound measures 85 dB, here is a short list of common sounds and how they measure up:
Here’s some good news. Hearing health professionals say noise-induced hearing loss (NIHL) can be prevented if we pay attention to — and protect our ears from — the sounds around us. If you’re planning to attend a concert or sporting event or spend a lot of time woodworking, riding motorcycles or operating outdoor lawn equipment, you’ll be exposed to noise levels in excess of 85 dB. That’s when it’s a good idea to invest in some hearing protection.
If you’re unsure about what type of hearing protection is right for you, consult a hearing healthcare professional.
What do decibels mean to those with hearing loss?
Those who’ve already been diagnosed with hearing loss also need to be mindful of decibel levels in their environment. It’s all about protecting the hearing you have left.