Tinnitus and Noise Exposure

It is very distressing to experience a sudden onset of ringing in the ears. This condition is known as tinnitus. The noise of tinnitus may include ringing, screeching, buzzing, chirping, a hissing sound like steam escaping, or similar to the humming sound from high tension power lines.

Although the noises seem to be heard in the ears, they are actually in the brain itself.

Tinnitus can result from a variety of causes. The most common cause is damage to the delicate sound-receiving hair cells within the inner ear. Exposure to a loud noise often damages these cells, resulting in a partial loss of hearing and the subsequent development of tinnitus. This condition is diagnosed as acoustic trauma. It is quite common in hunters, target shooters, police and military personnel, and anyone exposed without sufficient ear protection to loud gunfire or other loud noises.

How loud are various noises, and what levels are safe? What we typically think of as the loudness of sound is actually a reflection of sound pressure, and is measured in decibels (dB.).

A few examples of sound pressures are:

A quiet room: 30 dB

Speaking normally with a friend: 45 to 60 dB

Alarm clock: 75 dB

Home Blender: 85 dB

Home Garbage Disposal: 90 dB

Large truck with no muffler: 90 dB

Shouting in a noisy club: 90 dB

Band saw: 110 dB

Nightclub with live rock music: 115 dB

Gunfire within 15 feet: 150 dB

Commercial jet engine, 125 feet: 140 dB

Navy ship’s gun: 200 dB

Any sound below 80dB is safe for your ears and hearing. If you’re frequently around noise greater than 85 dB, your hearing can suffer. One isolated blast of 135 to 140 or more dB can damage your hearing forever.

The cochlea is a snail-shaped organ inside the inner ear. Inside the cochlea are delicate hair cells. They receive sound vibrations when transmitted from the ear canal and past the eardrum. When the sound vibration is excessive, the cells can literally vibrate to death. When hearing is lost this way, the sound frequencies that suffer most are near 4000 cycles per second.

Sound vibrations occur in the environment and are transmitted via the inner ear and eighth cranial nerve as electromagnetic signals to the brain. When sound is totally absent in the environment, these brain cells search for replacement sounds, and 95% of people with normal hearing will develop tinnitus.

Brain cells that are not receiving signals from external sound being transmitted actually become so sensitive that they listen to the electromagnetic signals of nearby brain cells. They interpret these signals as strange sounds that we describe as hissing, humming, ringing, etc. Cells are damaged by loud noise exposure cannot transmit normal signals, so this sets up the ideal situation for tinnitus to develop.

Visit Tinnitus to learn all that you have ever desired to know about tinnitus. Dr Smithdeal is a prior tinnitus sufferer and a board certified Otolaryngologist (ret.)