Friday, August 14, 2020

Types of Audiometric Tests


Hi friends!!!

In our previous blog, we have discussed about audiometer. Please check out for the link given below.


In today's blog we are going to discuss about different  types of audiometric tests done in audiometer.

The audiometer is an important equipment used in ENT hospitals to measure hearing ability of the patients. There are different types of audiometric tests done using audiometer. Therefore it is important for every healthcare professionals to know about audiometric tests.

Let's get into the topic with a small introduction about audiometer.


The audiometer is an electronic device used to evaluate the hearing threshold of the person and to quantify the degree of hearing loss. The audiometer is used by a experienced audiologist. The subjective audiometer requires a response from the patients as a feedback. The objective audiometer does not require a response or feedback from the patients.

Let's discuss about different types of audiometric tests.



The hearing tests called as audiometric tests determine the patients hearing levels with the help of audiometer. The following are the types of audiometric tests.


Pure tone audiometry is one of the often used audiometric tests. Pure tone audiometry uses air conduction to find out the hearing threshold at different frequencies. The pure tone is presented to the ear through a earphone. The lowest intensity at which the tone is perceived 50% of the time is measured in dB. This measurement is called as threshold. The output is plotted as a graph known as audiogram.


The bone conduction audiometry is one of the audiometric tests used to measure the inner ear’s response to sound. The conductor will be placed behind the ear. This conductor will send tiny vibrations directly to the inner ear through the bone. Here the sound skips the outer and middle ear.  If the results of the test are different from the pure tone audiometry test, it helps the doctor to identify which part of our ear is affected by hearing loss. Example: Outer ear, Middle ear or Inner ear.

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Speech audiometry is used to test the integrity of entire auditory system. There are two types of speech audiometric tests, speech discrimination tests and speech reception threshold test. In both the tests, the lowest decibel at which the patient can repeat the 50% of the words correctly is recorded. In speech discrimination test, monosyllable words are used. In speech reception threshold test two syllable words are used with equal stress.


The acoustic reflex test is one of the audiometric tests used to identify the involuntary muscle contractions of the middle ear. The muscles in the middle ear contracts when you hear loud sound. How much loud sound is required for this contraction to happen can give information about level of hearing loss. It is used to specify the location of the hearing problem like ossicles, cochlea and auditory nerve. 


The tympanometry is one of the objective audiometric tests  used to measure the movement of eardrum in response to the air pressure. A small probe like structure is used to push air into the ear. The movement of eardrum with respect to air pressure is plotted in the graph is called tympanogram. Tympanometry test determines whether there is any buildup of wax, fluid buildup and tumors. The graph shows information about whether eardrum moves very fast, too slow, too stiff or has a hole.

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The otoacoustic emission test is also a type of objective audiometric tests used to find out how our ear’s cochlea works. The hair cells in cochlea responds to external sound by vibrating. This vibration of hair cells produces mild sound that echoes back to middle ear. This mild sound is called otoacoustic emission. If the hearing loss is greater than 25-30 dB, these mild sounds cannot be produced. This test gives details about conditions like blockages in outer ear, fluid accumulations in middle ear or any damage to hair cells. Because of these conditions sound will not reach inner ear, as a result no mild sounds can be produced by hair cells.

A small probe like structure is placed into the inner ear cochlea. This probe produces sound into the cochlea and measures the echoes returning back. The otoacoustic emission is used when there is less reliability and lack of support from the patient’s side.


The auditory brainstem response is used to test the effectiveness of inner ear and brain pathways of hearing. It measures the electrical activity of brain due to the sounds. The surface electrodes are placed on scalp and ear lobes. The brain’s signal is plotted against the time. The peak waveforms 1 to 7 is produced within 10 millisecond after the stimulus of high intensity sounds. This test is also used when there is less reliability and lack of support from the patient’s side.

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Now I hope you have acquired some knowledge about different types of audiometric tests in audiometer. We will discuss in detail about a topic related to Biomedical Engineering in our next blog.

NOTE: Dear friends!!! ...Please do comment a topic related to Biomedical, so that we can discuss it in future blogs.

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