Audiometry

Introduction

Partial or complete hearing loss (deafness) may be temporary or permanent, depending on the type and cause. Some people are born with an inability to hear and for others, hearing loss may develop over time. You should contact your doctor if you notice changes in the way things sound or have a difficult time understanding others. Some causes of temporary hearing loss may resolve simply with medical treatment. Due to many technical advances, there are more solutions than ever for permanent hearing impairments and hearing loss including hearing aids, assistive communication devices, and cochlear implants.

Anatomy

The ear is divided into three parts: the outer, middle, and inner ear. Your ear not only enables you to hear, but it plays a role in balance as well.

The ear canal travels from your outer ear to your eardrum. Hearing is a complex process that involves your ear , nerves, and brain. Your outer ear, the part that you can see, collects the sound waves. The sound waves travel through the ear canal to the middle ear, which is located inside of your head. Sound waves cause the eardrum (tympanic membrane) to vibrate, which in turn cause the three tiny bones (malleus, incus, stapes) in your ear to move. Their movements cause vibrations that are detected by the cochlea in the inner ear. The cochlea is a structure that contains liquid and tiny hair cells. Some of the hair cells make the vibrations louder and others send nerve signals to your brain that are interpreted as sound.

Causes

Hearing impairment or loss occurs if there is a problem in the hearing process of one or both ears. Hearing loss may be temporary or permanent. It can occur in one or both ears. Common causes of hearing impairment or loss include ear infections, ear wax build up, aging, injury, loud noises, certain medications, and heredity. The main categories of hearing loss:

Conductive Hearing Loss (CHL)

Conductive hearing loss (CHL) is caused by problems with the outer or middle ear. Fluid build-up, such as with ear infections, can impair the vibrations of the eardrum or small bones. CHL may be temporary and treated with medications.

Sensorineural Hearing Loss (SNHL)

Sensorineural hearing loss (SNHL) results when the tiny hairs in the cochlea are damaged and cannot send signals to the brain.

Mixed Hearing Loss

People have both CHL and SNHL.

Neural Hearing Loss

Neural Hearing Loss is caused by damage to the nerve that sends signals from the cochlea to the brain.

Symptoms

You may have trouble understanding what people are saying, especially in noisy environments. Sounds and speech may sound garbled or muffled. You may hear noise, but are unable to identify what the sound is or where it comes from.

Diagnosis

Your doctor will review your medical history and conduct an examination to determine the cause of your hearing loss. A clinical screening test may be done to find out how well you hear words at various volumes. Audiometry is more thorough and involves wearing headphones and indicating when you hear a sound. In some cases, medical imaging tests, such as magnetic resonance imaging (MRI) scans or computed tomography (CT) scans may be used to learn more about the inner ear structures.

Treatment

Treatment varies greatly and depends on the cause and severity of the hearing loss. Causes of conductive hearing loss may resolve with antibiotics to treat infections or by simply removing earwax build-up. Sensorineural hearing loss may not be “cured” but hearing aids, amplifying systems, or cochlear implants may help improve your hearing. Additionally, a speech pathologist or audiologist can help you learn speech reading and American Sign Language. Ask about the latest assistive technology that may be appropriate for you. Let your doctor or speech therapist know what your interests are, and they will help match you with a solution.

Am I at Risk

Some people may be born with hearing impairments. For others, a decrease in hearing may occur over time. Sudden complete hearing loss is not common. Common risk factors for hearing loss include:

  • Increasing age
  • Loud noises, such as factory work, gunfire, loud music
  • Ear infections, ear wax build-up
  • Certain medications, such as some antibiotics (gentamicin), chemotherapy medications, high doses of aspirin or NSAIDS
  • Certain illnesses, especially those that cause high fever