What is an Audiological Evaluation
(Source: American Speech-Language-Hearing Association, ASHA)
An audiological evaluation is sometime thought of as "just a hearing test," but more than "just" the ability to hear sounds is involved. The audiological evaluation consists of several different components: a case history, physical examination, pure tone test, speech audiometric tests, and acoustic immittance audiometry.
The audiologist will ask several questions during the CASE HISTORY such as, "How long have you noticed difficulty with your hearing?" Has your difficulty with hearing has a gradual or sudden onset? Do you have ringing in your ears? Is there a history of ear infection? Have you noticed any pain or discharge from your ears? Is there a family history of hearing loss? Do you have greater difficulty hearing women´s, men´s, or children´s voices?" For children, questions regarding speech and language development, recognition of and response to familiar sounds (such as a telephone ringing, knock at the door, or music), and whether the child startles in response to loud sounds (such as a dog barking. balloon popping, or a door slamming). The answers to these and other questions, as well as any volunteered information, will assist in obtaining useful background data.
An otoscope, an instrument that contains a light and a magnifying lens, will be used during the PHYSICAL EXAMINATION. The ear is examined for the presence of excessive cerumen (wax), foreign objects (toys, food, pieces of cotton swabs, etc.), holes in the eardrum, signs of infection, or any other indicators of the need for a referral for a medical examination.
Typically, the PURE TONE TEST is completed in a soundproof booth, a room with special sound treating to the walls, ceiling, and floor to ensure that background noise does not affect test results. Only those sounds that the audiologist introduces into the room, either through earphones or through speakers located in the room, will be heard. Sounds may also be sent through a special headset that has been placed just behind the ear or on the forehead. The client is instructed to give some type of response such as raising a finger or hand, pressing a button, pointing to the ear where the sound was received, or saying ´yes´ to indicate that the sound was heard. Sometimes children are given a more play-like activity to indicate response. They may be instructed to string a peg, drop a block in a bucket, or place a ring on a stick in response to hearing the sound. Infants and toddlers are observed for changes in their behavior in response to sounds, such as sucking a pacifier, quieting, or searching for the sound.
The audiologist uses an audiometer to present tomes at different frequencies (pitches) and intensity levels. The frequency or pitch of the sound is referred to in Hertz (Hz). The intensity of the sound is measured in decibels (dB). Responses are recorded on a chart called an audiogram. In certain situations, other types of sounds, such as white noise, environmental sounds, music, or noisemakers may be used.
SPEECH AUDIOMETERY includes speech recognition threshold (SRT) and word recognition (discrimination) score. The speech recognition threshold estimates the lowest level at which speech is identified at least half of the time. Two syllable words are used, such as BASEBALL, PLAYGROUND, SIDEWALK, and AIRPLANE. The results are expressed in dB.
Word recognition tests attempt to evaluate how well you understand what you have heard. Single-syllable words, such as CHEW, WHAT , and KNEES, are spoken at a comfortable loudness level. Words may be presented in quiet and then in the presence of background noise. People who have difficulty speaking or those who are unable or unwilling to speak may respond by pointing to pictures or objects. A numerical score is obtained based on responses. A score of 0% indicates no understanding of the speech signal. A score of 100% indicates every word was identified correctly.
Acoustic immittance measurements are valuable in evaluating the outer and middle ear. This testing can assist in the detection of ear infection, holes in the eardrum, wax blocking the ear canal, or other problems that indicate the need for a medical evaluation. Tympanometry, one aspect of immittance testing, gently introduces air pressure into the ear canal. Sounds similar to those heard during the pure tone test will be used; however, the patient need not respond. The audiologist may also measure the acoustic reflex, a contraction of muscles in the middle ear in response to loud sounds--a reaction that serves to protect the ear from potentially damaging noise levels. The level of response or the absence of the acoustic reflex offers additional diagnostic information.
The audiologist will review each component of the audiological evaluation to obtain a profile of hearing abilities and needs. Additional special testing may be indicated based on the initial test results. As you can see, an audiological evaluation is more than "just a hearing test!"
The American Speech-Language-Hearing Association (ASHA) is the national professional and scientific society that represents 81,427 audiologists; speech-language pathologists; and speech, language and hearing scientists. ASHA´s mission is to promote the interest of its members, to provide them with the highest quality services, and to advocate for people with communication disabilities. ASHA´s Consumer Affairs Division provides an information and referral service on a broad range of speech, language and hearing disabilities for both children and adults.
For additional information on this topic or other speech, language, or hearing disabilities, contact the American Speech-Language-Hearing Association, 10801 Rockville Pike, Rockville, MD 20852, 1-800-638-8255 or (301) 897-8682 (Voice or TTY).