A previous article discussed the differing qualification, licensure, and scope of practice between hearing aid dispensers and audiologists. This article will address the process of hearing and the causes of hearing loss.
The Process of Hearing
Sound vibrations move through the air like waves moving across water. Hearing begins when the vibrations reach the outer ear (1), which acts to funnel the vibrations through the ear canal (2) toward the eardrum (3). The inset (bottom) shows sound vibrations interacting with the eardrum, before transferring to a series of three tiny bones in the middle ear (4). These bones further amplify the vibrations of the eardrum, before transferring them to a sensory organ known as the cochlea, in the inner ear (5). The cochlea is filled with fluid, and lined with tens of thousands of tiny hair cells. As vibrations pass through the fluid, they cause the hair cells to move. This motion causes electrical signals to be sent along the auditory nerve, which are then processed by the brain into the sounds we hear.
Hearing loss is often caused by normal aging or excessive exposure to damaging sounds, but underlying medical conditions can also be a factor. Hearing loss falls into two major categories:
Conductive hearing loss occurs in the outer and middle ear, when the transmission of sound vibrations is prevented from reaching the inner ear. This can happen due to wax build-up (A), fluid behind the eardrum (B), or a hole in the eardrum (C).
Sensorineural hearing loss occurs in the inner ear (D), when sound vibrations are unable to be converted into electrical signals that the brain can process. This can be caused by exposure to loud noise, genetics, medications, or natural aging.
Hearing Loss Facts for Americans
- Approximately 35 million in the U.S. suffer from hearing loss bad enough to affect their daily lives.
- About 65% of people with hearing loss experience a mild hearing loss, 30% a moderate, and 5% a severe or profound hearing loss.
- There is a direct link between age and hearing loss: about 18% of adults 45 to 54, 30% of adults 65 to 74, and 47% of adults over 75 and have hearing deficiencies.
- 20% of the population aged 12 years and older has hearing difficulties severe enough to limit their communication.
- Three out of every 1,000 children are born deaf or hard-of-hearing.
- Hearing damage due to MP3 players is becoming increasingly prevelant among younger people.
- About 60% of deployed military service men and women have noise induced hearing loss, tinnitus (ringing in the ear), and other hearing injuries.
You Don’t Have to be a Victim
Even considering the severe consequences of untreated hearing loss, only one in five people who would benefit from hearing aids actually uses them. On average, people with hearing loss wait almost 10 years before they take action. Consumer education is a critical part of overcoming the high cost of hearing loss. In future articles we will discuss the medical, emotional, and lifestyle consequences of untreated hearing loss…and what you can do about it.