Loud Noise Can Kill Cells in the Inner Ear
Sound waves cause vibration in the ear drum, which triggers movement of the hair cells in the inner ear, called the cilia. The cilia discharge electrical impulses that are routed through the auditory nerve to the brain. Excessively loud or prolonged exposure to loud noise, like the sound of a lawnmower, a concert or simply listening to music with ear buds can be enough to cause permanent damage and death to the cilia and lead to hearing loss.
“The cilia are essentially sheared off and are no longer able to discharge the electrical impulses as they should,” said Bridget Elliott, AuD, an Audiologist with the Froedtert & MCW health network. “A person might still be able to hear, but would require the sound to be at a higher decibel to move the cilia.”
Audiologists can measure a person’s noise-induced hearing loss during a hearing test with an audiogram. The audiogram is a graph of the sound waves a person can hear at varying frequencies. Noise attacks hearing at high frequencies, and noise-induced hearing loss is a serious concern. An analysis from the National Institute on Deafness and Other Communication Disorders found that nearly one in four Americans between the ages of 20 and 69 have noise-induced hearing loss. People who suffer from noise-induced hearing loss may have trouble understanding speech.
“Consonants carry the meaning of words in the English language and are usually higher in pitch,” Dr. Elliott said. “People with noise-induced hearing loss are not getting some of that consonant information, so they may hear speech, but not be able to make out the words.”
Decibels and Duration
The degree of damage noise can cause to the inner ear is dependent on the decibel (dB) of the noise and the duration of exposure. The human ear can tolerate noise below 85 dB, without damage. However, the average decibel level of music at a concert is about 100 dB. Prolonged exposure to noise at that level can cause a threshold shift in a person’s hearing, threshold being the lowest decibel level at which a person can hear a particular frequency. Threshold shifts can be temporary or permanent.
“Most people have experienced a temporary threshold shift in their hearing, at some point,” Dr. Elliott said. “When you have been in a loud environment and move to a quieter one, yet you’re still speaking in a loud voice, it is because of a threshold shift.”
Some people might also experience ringing in the ears or hear a hissing, clicking, humming or buzzing. None of these noises are caused by a sound in the environment. In some cases, a person might even be nauseous. These symptoms are due to a condition called tinnitus.
“Tinnitus is the most common reason why people come to the clinic for a hearing test,” Dr. Elliott said. “It can be acute or chronic. More commonly, it is acute, and I call this an auditory hangover. You went to a concert the night before, and you experience these symptoms when you’re home, in a quiet room.”
Researchers want to know more about the impact of music and the frequency of tinnitus. One survey of people that more than 5,200 people who were exposed to different forms of music (personal music player, concert or club) found that 59 percent reported having tinnitus that lasted more than five minutes. Even though tinnitus disappears and normal hearing appears to return, there are physiological changes that occur in the inner ear that may not manifest until much later on. In other words, damage from loud noises and the subsequent hearing is cumulative.
Dial Back the Damage
There are two simple things you can do to protect your ears and prevent hearing loss:
- Wear hearing protection
- Increase your distance from the sound source
Foamy earplugs, which are better for muting noise, are not as helpful to the concert-goer who still wants to experience the music. Earplugs come in many different designs, and some are specifically made for to turn down the decibel level of the sound in the environment instead of attempting to mute it altogether.
“There are earplugs made to wear during concerts or in a nightclub that replicate the resonance of the ear canal,” Dr. Elliott said. “These will attenuate the sound evenly across all frequencies so that you do not lose any of the nuances. They simply turn the volume down for you.”
You can also use physics to your advantage. A sound’s intensity and loudness decreases by doubling the distance away from the source. If you’re at a show, being right in front of the band or near the speakers will increase your risk of hearing loss. There are also a number of apps available for Apple and Android devices that can calculate the decibel level for you, and let you know when the noise level is safe.