What Does Audiometry mean?
Audiometry is a test performed to evaluate the amount of hearing loss. The test can be used to evaluate the tone of the sound, intensity, balance issues, and other inner ear defects. The audiologist performs the test for diagnosing and treating hearing loss. The intensity of the sound is measured in decibels. Loud sounds are approximately 80 to 120 dB and whisper or quiet sounds are about 20 dB. The sound tone is expressed in Hertz. The human hear tones are 20 to 20,000 Hz, and low base tones are approximately 50 Hz. Loud sounds can cause immediate hearing loss and ear pain in a person. Loud sounds measuring more than 85 dB can lead to the hearing loss within a few hours.
What Are the Various Features of Audiometry?
The features of audiometry are as follows:
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It helps generate a pure tone.
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The intensity and frequency of the tone can also be selected.
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The generated can be continuous or intermittent. The changeover can be controlled with an interrupter switch.
What Are the Different Types of Pure Tone Audiometers?
The types of pure-tone audiometers are as follows:
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Type I Audiometer- Full-fledged audiometer
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Type II Audiometer- This type does not allow free field audiometry because it does not have speakers.
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Type III Audiometer- These portable audiometers do not have speech audiometry.
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Type IV Audiometer- It comprises only earphones and has a primary screening facility.
What Are the Different Components of an Audiometer?
The components of an audiometer are
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Interrupter Switch- This helps switch the tone on or off because continuous tones can decay. An interrupter switch helps to control the duration of sound or signals presented to the person during the test.
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Oscillator- It helps generate pure tones, and the accuracy of the oscillator is between +/- 3 percent within the specified range of frequency. The frequencies are 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, and 8000 Hertz. Pure tones are presented in the OFF position, and speech signals are presented in the off position.
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Output Power Amplifier- The outpower amplifier amplifies the signals or pure tones generated by the oscillator. It produces significantly less distortion and presents good signal quality in noise ratio.
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Output Transducers- These include bone vibrators, earphones, and loudspeakers.
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Equalization Circuits- These equalize the generated sound with the help of transistors because the human threshold for different frequencies is variable. Equalization circuits are insensitive to low and high frequencies.
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Hearing Level Attenuators- The signals produced by the audiometers within the range of 110 to 120 dB are controlled by the hearing level attenuators. The intensity usually varies in 5 dB steps and must be precise and accurate.
What Are Pure Tones?
Pure tones are specific single-frequency sounds of the simplest type. The amplitude of the pure tone is measured in decibels, and the tone is usually described by its amplitude, phase, duration, and frequency. The pure tone audiometry test is performed to diagnose hearing loss in a person and evaluate the frequency-specific threshold elevation.
What Is the Function of Pure Tone Audiometry?
A pure tone audiometry test is performed to check hearing loss caused by the following conditions:
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Frequent exposure to loud noises.
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Ear injury or trauma.
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Ruptured eardrum.
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Congenital disabilities.
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Meniere’s disease is an autoimmune disease of the inner ear.
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Otosclerosis, an abnormal bone growth in the ear, is an inherited condition that prevents normal ear functioning.
How Is the Pure Tone Audiometry Test Performed?
A pure tone audiometry test is performed by making a person listen to pure tone through headphones connected to the audiometer. These pure tones are of a specific volume and frequency, and the test is performed on each ear one at a time. The person is asked to give any signal when they hear a sound. The minimum volume of the sound that the person can hear is noted on the graph. The test is also known as an audiogram, and the bone oscillator device is used to measure bone conduction by placing it near the mastoid bone. Pure tone audiometry test is performed multiple times at different frequencies (between 250 to 8000 Hertz) for both ears. If a person can hear the sound frequency between o to 25 dB, they have an average hearing ability.
What Is Done After the Pure Tone Audiometry Test?
Once the pure tone audiometry test is performed, the doctor analyzes the outcomes of the test based on the person’s performance and how well they can hear tone and volume. Then the doctor suggests various preventive measures for the person according to the condition. These include needing a hearing aid as a corrective measure or using earplugs in noisy environments.
What Are the Various Conditions Affecting the Pure Tone Audiometry Outcomes?
The conditions affecting the audiometry test results are as follows:
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Chronic ear infection.
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Acoustic neuroma.
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Hearing loss is related to the age of a person.
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Perforated or ruptured eardrum.
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Hearing loss due to sudden loud noise or regular exposure to loud noise from music or in the work area.
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Otosclerosis or abnormal growth of bone in the inner ear.
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Labyrinthitis.
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Meniere’s disease.
What Are the Different Types of Tests To Diagnose Hearing Loss?
The different tests to detect hearing loss include
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Speech-testing.
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Auditory brainstem response (ABR).
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Middle ear hearing test.
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Otoacoustic emissions.
Conclusion
To summarize, pure tone audiometry is the standard test to measure a person's hearing threshold levels, configuration, degree, and type of hearing loss. The test thus helps the healthcare provider diagnose and treat a person's hearing loss condition. The test is usually performed on children and adults who are mature enough to cooperate and understand the pure tone audiometry test procedure. Therefore, people working in noisy environments should be tested annually to check for any hearing defects caused in the workplace. This can help the worker diagnose the hearing loss in the early stages and prevent further deterioration of hearing abilities.
