Hearing Loss and the Audiologist

• hear speech and other sounds loudly enough, and/or
• understand speech even when it is loud enough.

Hearing loss is a common problem in modern society due to the combined effects of noise, aging, disease, and heredity. Hearing is a complex sense involving both the sensitivity of the ear as well as the ability to understand speech. Determining the prevalence of hearing loss depends on the type and degree of the loss, the area(s) of abnormality in the auditory system (middle ear, inner ear, brain, e.g.), noise exposure, and age.

• Approximately 28 million Americans have a hearing impairment.
• The number of Americans with a hearing loss has evidentially doubled during the past 30 years. Data gleaned from Federal surveys illustrate the following trend of prevalence for individuals aged three years or older: 13.2 million (1971), 14.2 million (1977), 20.3 million (1991), and 24.2 million (1993). An independent researcher estimates that 28.6 million Americans had an auditory disorder in 2000. This estimate is reasonably well within projections from the 1971-1993 trend line that evolved from Federal surveys.
• Ten million Americans have suffered irreversible noise induced hearing loss, and 30 million more are exposed to dangerous noise levels each day.
• Hearing loss affects approximately 17 in 1,000 children under age 18. Incidence increases with age: Approximately 314 in 1,000 people over age 65 have hearing loss and 40 to 50 percent of people 75 and older have a hearing loss.

Communication disorders are among the most common disabilities in the United States. A child's overall future and success can be improved greatly through the early identification of communication disorders, establishment of their causes, and subsequent intervention.

• The number of children with disabilities, ages 6-21, served in the public schools under the Individuals with Disabilities Education Act (IDEA) Part B in the 2000-01 school year was 5,775,722. Of these children, 1,093,808 (18.9%) received services for speech or language disorders.
• Case histories often reveal a family history of communication disorders. Between 28% and 60% of children with a speech and language deficit have a sibling and/or parent who is also affected.
• Services provided for children with speech or language impairment show an overall increase of 9.5% between the 1991-92 and 2000-01 school years.
• Incidence of childhood stuttering is highest between a child's second and fourth birthdays, ultimately affecting 4% to 5% of the population.

In addition, the following prevalence data have been reported relative to hearing loss:

• Only 1 out of 5 people who could benefit from a hearing aid actually wears one.
• Three out of 4 children experience ear infection (otitis media) by the time they are 3 years old.
• At least 12 million Americans have tinnitus (ringing in the ear). Of these, at least 1 million experience it so severely that it interferes with their daily activities.

Source: Compiled from fact sheets produced by the National Institute on Deafness and Other Communication Disorders (NIDCD) and by Andrea Castrogiovanni, American Speech-Language-Hearing Association, 2200 Research Boulevard, Rockville, Maryland 20850.

What causes hearing loss in children?

Otitis Media

Otitis media is the most frequently diagnosed disease in infants and young children. Otitis media is an inflammation in the middle ear (the area behind the eardrum) that is usually associated with the buildup of fluid. Seventy-five percent of children experience at least one episode of otitis media by their third birthday.

Congenital Causes

Congenital hearing loss implies that the hearing loss is present at birth. It can include hereditary hearing loss or hearing loss due to other factors present either prenatal or at the time of birth. Other causes of congenital hearing loss that are not hereditary in nature include prenatal infections, illnesses, toxins consumed by the mother during pregnancy or other conditions occurring at the time of birth or shortly thereafter.

Acquired Causes

Acquired hearing loss is a hearing loss which appears after birth, at any time in one's life, perhaps as a result of a disease, a condition, or an injury. The following are examples of conditions that can cause acquired hearing loss in children:

• Ear infections (otitis media)
• Ototoxic (damaging to the auditory system) drugs
• Meningitis
• Measles
• Encephalitis
• Chicken pox
• Influenza
• Mumps
• Head injury
• Noise exposure

What causes hearing loss in adults?

Hearing loss in adults has many causes such as disease or infection, ototoxic drugs, exposure to noise, tumors, trauma, and the aging process. Some causes of hearing loss in adults are :

Otosclerosis is a disease involving the middle ear capsule.

Meniere's disease affects the membranous inner ear and is characterized by deafness, dizziness (vertigo), and ringing in the ear (tinnitus).

Medications used to manage some diseases are damaging to the auditory system (ototoxic) and cause hearing loss.

Exposure to harmful levels of noise results in noise-induced hearing loss . The prolonged exposure causes damage to the hair cells in the cochlea and results in permanent hearing loss. The noise-induced hearing loss usually develops gradually and painlessly. Hearing loss can also occur as a result of an acoustic trauma, or a single exposure or very few exposures to very high levels of sound.

An acoustic neuroma is an example of a tumor that causes hearing loss. The first symptom is reduction of hearing in one ear accompanied by a feeling of fullness.

Trauma can also result in hearing loss. Examples include fractures of the temporal bone, puncture of the eardrum by foreign objects, and sudden changes in air pressure.

Loss of hearing as a result of the aging process is called presbycusis . The process involves degeneration of the inner ear (cochlea). Presbycusis can also involve other parts of the auditory system. The hearing loss is progressive in nature with the high frequencies affected first. While the process begins after age 20, it is typically at ages 55 to 65 that the high frequencies in the speech range begin to be affected.

What are some of the effects of hearing loss ?

Persons with hearing loss may misunderstand what is being said. It may appear as if they are ignoring a supervisor's or customer's request and may result in poor work performance. People with hearing loss may not be able to fully experience meetings, movies, parties, theatrical performances and/or religious services. Friends and family may become frustrated with the difficulty they have communicating with the individual with hearing impairment. Research suggests an increase in depression in those who have hearing loss.

The temporary hearing loss due to ear infections may affect speech and language development in young children. Unaided, school-aged children with hearing loss may have problems learning and difficulty in social skills.

Hearing loss may be the symptom of a medical problem and hearing testing my result in a referral to a physician for treatment or surgery.