LESSON SEVEN: MEASURING HEARING IMPAIRMENT FOCUS: This lesson will teach students the basics about hearing testing. The activity gives students an opportunity to graph the audiograms of a younger person and older person to compare and contrast the differences in hearing. BACKGROUND: When a hearing specialist (an audiologist) tests hearing, typically he/she measures the decibel level at which an individual hears a pure tone at a given frequency. These decibel levels may then be graphed to form an audiogram. Averaging the decibel levels across different frequencies yields a pure tone average. For example, the average decibel levels at 500, 1000, and 2000 Herz (Hz) gives a speech frequency pure tone average (SFPTA). The average decibel levels at 1000, 2000, and 4000 Hz gives the high frequency pure tone average (HFPTA). These pure tone averages may then be used to determine whether someone might benefit from an amplification device, like a hearing aide. Just like visual acuity is only one aspect of vision, pure tone audiometry is only one measure of hearing ability. For example, other measures of hearing include speech understanding, speech reception thresholds, and bone conduction. COMMON HEARING DISORDERS There are two main kinds of hearing problems conductive hearing problems and nerve deafness. Conductive hearing problems affect the outer or middle ear. This can produce a problem which can usually be treated and even cured. Conductive deafness leads to a loss of loudness (like trying to listen to someone who is speaking very quietly or is very far away). The other main type of problem is connected with the inner ear or the nerve of hearing. Nerve deafness usually results in permanent hearing loss. Nerve deafness cuts down the loudness and distorts the sound as well. BLOCKED EARS One of the simplest causes of hearing loss. The ear canal becomes blocked which stops the sound waves from reaching the eardrum; blockage may be due to natural ear wax which has hardened, or a small object which has been pushed into the ear, or skin conditions such as eczema or boils can also block the ear canal. Too much wax or hardened wax may need to be removed by a doctor using eardrops, a syringe, or an ear spoon. GLUE EAR Fluid produced in the middle ear usually drains down the eustachian tube to the throat. If the eustachian tube becomes blocked by infection or swollen adenoids, the fluid becomes thick and sticky. The glue that is produced makes it harder for the eardrum and bones to vibrate correctly. DAMAGED EAR DRUM Blocked eustachian tubes can cause air pressure to build up inside the ear. This pressure may damage the eardrum. Several serious infections in the middle ear can weaken the eardrum; holes or perforations may appear in the eardrum which stop it from vibrating normally. Some holes in the eardrum can heal 2001 UTHSCSA "Positively Aging " a trade mark of the University of Texas Health Science Center at San Antonio -1
naturally, but some may need special treatment. Holes in the eardrum may also be caused by poking things into the ear (remember, never put anything in your ear smaller than your elbow!), a serious blow to the ear, or a very loud noise. EAR BONE DISEASE (OTOSCLEROSIS) familial; ossicles become covered with a spongy growth, particularly affecting the stapes causing it to become fixed to the oval window thus unable to move freely. This can be surgically corrected. The onset between the ages of 18 and 30, becomes more serious as people age and more frequently occurs in women. TINNITUS (BUZZING/RINGING IN THE EARS) often occurs in elderly people. Hard to determine exactly where the noises are coming from; possibly caused by loud noises, infections, or diseases; possibly linked to certain drugs, foods, or drinks; deafness may not result, but tinnitus can be very distracting and annoying. NERVE DEAFNESS may develop at any time of life; cochlea can be damaged by genetic factors, difficulties at birth, childhood diseases (mumps, measles, diphtheria) other diseases (meningitis, typhoid fever), very loud noises, and some drugs. Many elderly people have some form of nerve deafness due to changes during aging (presbycusis). ACTIVITY 7A: CHARTING AUDIOGRAMS Pass out the worksheets CHARTING AUDIOGRAMS and AUDIOGRAM to each student. Have them graph the audiometric data from CHARTING AUDIO- GRAMS on the AUDIOGRAM graph. Use a circle as a symbol for the decibel levels from the right ear and a triangle for the decibel levels from the left ear. Plot the data from the younger and older person on the same graph. The older person s pattern is characteristic of presbycusis and shows a high frequency loss at the higher decibel levels. Have the students discuss the differences between the younger and older person s audiograms. Materials: 1. Worksheet CHARTING AUDIOGRAMS 2. Worksheet AUDIOGRAM 2001 UTHSCSA "Positively Aging " a trade mark of the University of Texas Health Science Center at San Antonio -2
ANNA GUERRERO AGE 24 CHARTING AUDIOGRAMS Anna works in an aircraft maintenance facility repairing jet engines. There is a lot of noise where she works and every year she has to have her hearing tested. This is because prolonged noise exposure can cause hearing loss. As long as Anna wears her ear plugs or mufflers, this type of hearing loss can be prevented. Here are the results of Anna s hearing test: FREQUENCY (Herz) Right Ear Left Ear 250 Hz 10 db 15 db 500 Hz 15 db 12 db 1000 Hz 10 db 10 db 2000 Hz 12 db 10 db 4000 Hz 10 db 12 db What is Anna s Speech Frequency Pure Tone Average (SFPTA) for each ear? What is her High Frequency Pure Tone Average (HFPTA) for each ear? SFPTA (db) HFPTA (db) Right Ear Left Ear 2001 UTHSCSA "Positively Aging " a trade mark of the University of Texas Health Science Center at San Antonio -3
PEDRO MONTOYA AGE 7 CHARTING AUDIOGRAMS Mr. Montoya dreads going to restaurants with his family because he can t hear with all the noise in the background it makes it difficult to order his food and he is embarrassed when he can t understand the waitress. Also, his family argues with him because he has the television turned up too loud for everyone else in the house. After much discussion, he agrees to see an audiologist and have his hearing tested. Here are the results of Mr. Montoya s hearing tests: FREQUENCY (Herz) Right Ear Left Ear 250 Hz 15 db 15 db 500 Hz 20 db 25 db 1000 Hz 40 db 45 db 2000 Hz 55 db 0 db 4000 Hz 5 db 70 db What is Mr. Montoya s Speech Frequency Pure Tone Average (SFPTA) for each ear? What is his High Frequency Pure Tone Average (HFPTA) for each ear? SFPTA (db) HFPTA (db) Right Ear Left Ear 2001 UTHSCSA "Positively Aging " a trade mark of the University of Texas Health Science Center at San Antonio -4
CHARTING AN AUDIOGRAM: On the graph paper marked AUDIOGRAM, plot the decibel levels at each frequency for each ear for Anna Guerrero and Pedro Montoya. Use a circle for the symbols for the right ear and a triangle for the symbols for the left ear. Use different color pencils to make the graph so that you can easily tell which chart belongs to Anna Guerrero and which one belongs to Mr. Montoya. 1. Describe the differences in SFPTA and HFPTA for Anna Guerrero and Pedro Montoya? Are there any differences in each of them between the right ear and the left ear? 2. Look carefully at the graphs you have drawn. What differences do you notice between the graphs for Anna Guerrero and the graphs for Pedro Montoya? AUDIOGRAM DECIBELS (db) 250 Hz 500 Hz 1000 Hz 2000 Hz 4000 Hz 0 db 5 db 10 db 15 db 20 db 25 db 30 db 35 db 40 db 45 db 50 db 55 db 0 db 5 db 70 db NOTE: The shaded area indicates what would be considered normal hearing levels for most people. 2001 UTHSCSA "Positively Aging " a trade mark of the University of Texas Health Science Center at San Antonio -5