Tympanometry

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Tympanometry
Tympanometry.svg
ICD-9-CM 95.41
MeSH D000158
MedlinePlus 003390

Tympanometry is an acoustic evaluation of the condition of the middle ear [1] eardrum (tympanic membrane) and the conduction bones by creating variations of air pressure in the ear canal.

Contents

Tympanometry is an objective test of middle-ear function. It is not a hearing test, but rather a measure of energy transmission through the middle ear. It is not a measure of eardrum or middle ear mobility. It is an acoustic measure, measured by a microphone, as part of the ear canal probe, inserted into the ear canal. The test should not be used to assess the sensitivity of hearing and the results of this test should always be viewed in conjunction with pure tone audiometry.

Tympanometry is a valuable component of the audiometric evaluation. In evaluating hearing loss, tympanometry permits a distinction between sensorineural and conductive hearing loss, when evaluation is not apparent via Weber and Rinne testing. Furthermore, in a primary care setting, tympanometry can be helpful in making the diagnosis of otitis media by demonstrating the presence of fluid build up in the middle ear cavity.

Operation

A tone of 226 Hz is generated by a probe tip inserted into the external ear canal, where the sound strikes the tympanic membrane, causing vibration of the middle ear, which in turn results in the conscious perception of hearing. Some of this sound is reflected back and picked up by the instrument. Most middle ear problems result in stiffening of the middle ear, which causes more of the sound to be reflected back.

While 226 Hz is the most common probe tone, others can be used. In infants under 4 months of age, research has shown a 1000 Hz tone yields more accurate results. Multi-frequency tympanometry is conducted at multiple frequencies between 250 and 2000 Hz and is used to help identify ossicular abnormalities. [2]

Admittance is how energy is transmitted through the middle ear. The instrument measures the reflected sound and expresses it as an admittance or compliance, plotting the results on a chart known as a tympanogram.

Normally, the air pressure in the ear canal is the same as ambient pressure. Also, under normal conditions, the air pressure in the middle ear is approximately the same as ambient pressure since the eustachian tube opens periodically to ventilate the middle ear and equalize pressure. In a healthy individual, the maximum sound is transmitted through the middle ear when the ambient air pressure in the ear canal is equal to the pressure in the middle ear.

Procedure

Tympanometry in a boy in Cameroon. Hopital Laquintini-4993 32.jpg
Tympanometry in a boy in Cameroon.

After an otoscopy (examination of the ear with an otoscope) to ensure that the path to the eardrum is clear and there is no perforation, the test is performed by inserting the tympanometer probe in the ear canal. The instrument changes the pressure in the ear, generates a pure tone, and measures the eardrum responses to the sound at different pressures. This produces a series of data measuring how admittance varies with pressure, which is plotted as a tympanogram:

Tympanograms are categorized according to the shape of the plot. A normal tympanogram (left) is labelled Type A. There is a normal pressure in the middle ear with normal mobility of the eardrum and ossicles. Type B tympanogram may reveal (a) fluid in the middle ear, (b) perforation of the tympanic membrane or patent pressure equalization tube, or (c) a tumor in the middle ear. Type C tympanograms are consistent with negative pressure in the middle ear space resulting from compromised eustachian tube function and a retracted tympanic membrane.

The categorising of tympanometric data should not be used as a diagnostic indicator. It is merely a description of shape. There is a distinction between the three types as well as the two subtypes of type A, namely AS and AD. For example, AS (a shallow tympanogram) will show a stiff middle ear system or AD (a deep tympanogram) consistent with ossicular discontinuity or a monomeric membrane. Only measures of static acoustic admittance, ear canal volume, and tympanometric width/gradient compared to sex, age, and race specific normative data can be used to somewhat accurately diagnose middle ear pathology along with the use of other audiometric data (e.g. air and bone conduction thresholds, otoscopic examination, normal word recognition at elevated presentation levels, etc.).

Tympanometry by end users

Smartphones

There have been a few efforts to lower the cost of tympanometers by using smartphones. [3] [4] [5] In 2022, University of Washington researchers had demonstrated an end-to-end smartphone-based tympanometer system that consists of a portable phone attachment used to change the air pressure in the ear. [6] The smartphone computes and displays a tympanogram and reports peak acoustic admittance in real-time. The smartphone-based system operated at 226 Hz and in proof-of-concept testing showed comparable results to commercial tympanometers. Given the ubiquity of smartphones across the world, these mobile systems may help make these audiology tools accessible across the world.

Consumer devices

Consumer devices have been made to allow checking for middle-ear fluid at home. A 2009 study found the Ear Check Middle Ear Monitor consumer model acoustic reflectometer [7] to give few false negative results in detecting middle-ear fluid; specificity and positive predictive values were modest, with many false positives. [8] The device was no longer available in 2023.

Related Research Articles

<span class="mw-page-title-main">Middle ear</span> Portion of the ear internal to the eardrum, and external to the oval window of the inner ear

The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea.

<span class="mw-page-title-main">Eardrum</span> Membrane separating the external ear from the middle ear

In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air to the ossicles inside the middle ear, and thence to the oval window in the fluid-filled cochlea. The ear thereby converts and amplifies vibration in the air to vibration in cochlear fluid. The malleus bone bridges the gap between the eardrum and the other ossicles.

<span class="mw-page-title-main">Cochlea</span> Snail-shaped part of inner ear involved in hearing

The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus. A core component of the cochlea is the organ of Corti, the sensory organ of hearing, which is distributed along the partition separating the fluid chambers in the coiled tapered tube of the cochlea.

<span class="mw-page-title-main">Vestibulocochlear nerve</span> Cranial nerve VIII, for hearing and balance

The vestibulocochlear nerve or auditory vestibular nerve, also known as the eighth cranial nerve, cranial nerve VIII, or simply CN VIII, is a cranial nerve that transmits sound and equilibrium (balance) information from the inner ear to the brain. Through olivocochlear fibers, it also transmits motor and modulatory information from the superior olivary complex in the brainstem to the cochlea.

<span class="mw-page-title-main">Otosclerosis</span> Condition characterized by an abnormal bone growth in the middle ear

Otosclerosis is a condition of the middle ear where portions of the dense enchondral layer of the bony labyrinth remodel into one or more lesions of irregularly-laid spongy bone. As the lesions reach the stapes the bone is resorbed, then hardened (sclerotized), which limits its movement and results in hearing loss, tinnitus, vertigo or a combination of these. The term otosclerosis is something of a misnomer: much of the clinical course is characterized by lucent rather than sclerotic bony changes, so the disease is also known as otospongiosis.

<span class="mw-page-title-main">Hearing test</span> Evaluation of the sensitivity of a persons sense of hearing

A hearing test provides an evaluation of the sensitivity of a person's sense of hearing and is most often performed by an audiologist using an audiometer. An audiometer is used to determine a person's hearing sensitivity at different frequencies. There are other hearing tests as well, e.g., Weber test and Rinne test.

<span class="mw-page-title-main">Ear</span> Organ of hearing and balance

An ear is the organ that enables hearing and body balance using the vestibular system. In mammals, the ear is usually described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ear is a self cleaning organ through its relationship with earwax and the ear canals. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localization.

<span class="mw-page-title-main">Equal-loudness contour</span> Frequency characteristics of hearing and perceived volume

An equal-loudness contour is a measure of sound pressure level, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon and is arrived at by reference to equal-loudness contours. By definition, two sine waves of differing frequencies are said to have equal-loudness level measured in phons if they are perceived as equally loud by the average young person without significant hearing impairment.

<span class="mw-page-title-main">Acoustic reflex</span> Small muscle contraction in the middle ear in response to loud sound

The acoustic reflex is an involuntary muscle contraction that occurs in the middle ear in response to loud sound stimuli or when the person starts to vocalize.

<span class="mw-page-title-main">Conductive hearing loss</span> Medical condition

Conductive hearing loss (CHL) occurs when there is a problem transferring sound waves anywhere along the pathway through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles). If a conductive hearing loss occurs in conjunction with a sensorineural hearing loss, it is referred to as a mixed hearing loss. Depending upon the severity and nature of the conductive loss, this type of hearing impairment can often be treated with surgical intervention or pharmaceuticals to partially or, in some cases, fully restore hearing acuity to within normal range. However, cases of permanent or chronic conductive hearing loss may require other treatment modalities such as hearing aid devices to improve detection of sound and speech perception.

<span class="mw-page-title-main">Sensorineural hearing loss</span> Hearing loss caused by an inner ear or vestibulocochlear nerve defect

Sensorineural hearing loss (SNHL) is a type of hearing loss in which the root cause lies in the inner ear, sensory organ, or the vestibulocochlear nerve. SNHL accounts for about 90% of reported hearing loss. SNHL is usually permanent and can be mild, moderate, severe, profound, or total. Various other descriptors can be used depending on the shape of the audiogram, such as high frequency, low frequency, U-shaped, notched, peaked, or flat.

<span class="mw-page-title-main">Audiometry</span> Branch of audiology measuring hearing sensitivity

Audiometry is a branch of audiology and the science of measuring hearing acuity for variations in sound intensity and pitch and for tonal purity, involving thresholds and differing frequencies. Typically, audiometric tests determine a subject's hearing levels with the help of an audiometer, but may also measure ability to discriminate between different sound intensities, recognize pitch, or distinguish speech from background noise. Acoustic reflex and otoacoustic emissions may also be measured. Results of audiometric tests are used to diagnose hearing loss or diseases of the ear, and often make use of an audiogram.

Presbycusis, or age-related hearing loss, is the cumulative effect of aging on hearing. It is a progressive and irreversible bilateral symmetrical age-related sensorineural hearing loss resulting from degeneration of the cochlea or associated structures of the inner ear or auditory nerves. The hearing loss is most marked at higher frequencies. Hearing loss that accumulates with age but is caused by factors other than normal aging is not presbycusis, although differentiating the individual effects of distinct causes of hearing loss can be difficult.

<span class="mw-page-title-main">Audiogram</span> Graph showing audible frequencies

An audiogram is a graph that shows the audible threshold for standardized frequencies as measured by an audiometer. The Y axis represents intensity measured in decibels (dB) and the X axis represents frequency measured in hertz (Hz). The threshold of hearing is plotted relative to a standardised curve that represents 'normal' hearing, in dB(HL). They are not the same as equal-loudness contours, which are a set of curves representing equal loudness at different levels, as well as at the threshold of hearing, in absolute terms measured in dB SPL.

<span class="mw-page-title-main">Hearing range</span> Range of frequencies that can be heard by humans or other animals

Hearing range describes the frequency range that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 20 to 20,000 Hz, although there is considerable variation between individuals, especially at high frequencies, and a gradual loss of sensitivity to higher frequencies with age is considered normal. Sensitivity also varies with frequency, as shown by equal-loudness contours. Routine investigation for hearing loss usually involves an audiogram which shows threshold levels relative to a normal.

<span class="mw-page-title-main">Hearing</span> Sensory perception of sound by living organisms

Hearing, or auditory perception, is the ability to perceive sounds through an organ, such as an ear, by detecting vibrations as periodic changes in the pressure of a surrounding medium. The academic field concerned with hearing is auditory science.

<span class="mw-page-title-main">Tympanosclerosis</span> Medical condition

Tympanosclerosis is a condition caused by hyalinization and subsequent calcification of subepithelial connective tissue of the tympanic membrane and middle ear, sometimes resulting in a detrimental effect to hearing.

Bone-conduction auditory brainstem response or BCABR is a type of auditory evoked response that records neural response from EEG with stimulus transmitted through bone conduction.

<span class="mw-page-title-main">Oral skills</span>

Oral skills are speech enhancers that are used to produce clear sentences that are intelligible to an audience. Oral skills are used to enhance the clarity of speech for effective communication. Communication is the transmission of messages and the correct interpretation of information between people. The production speech is insisted by the respiration of air from the lungs that initiates the vibrations in the vocal cords. The cartilages in the larynx adjust the shape, position and tension of the vocal cords. Speech enhancers are used to improve the clarity and pronunciation of speech for correct interpretation of speech. The articulation of voice enhances the resonance of speech and enables people to speak intelligibly. Speaking at a moderate pace and using clear pronunciation improves the phonation of sounds. The term "phonation" means the process to produce intelligible sounds for the correct interpretation of speech. Speaking in a moderate tone enables the audience to process the information word for word.

<span class="mw-page-title-main">Diagnosis of hearing loss</span> Medical testing

Identification of a hearing loss is usually conducted by a general practitioner medical doctor, otolaryngologist, certified and licensed audiologist, school or industrial audiometrist, or other audiometric technician. Diagnosis of the cause of a hearing loss is carried out by a specialist physician or otorhinolaryngologist.

References

  1. David Jay Steele; Jeffrey Susman; Fredrick A. McCurdy (2003). Student guide to primary care: making the most of your early clinical experience. Elsevier Health Sciences. pp. 370–. ISBN   978-1-56053-545-4 . Retrieved 27 June 2011.
  2. Petrak, Michelle. "Tympanometry Beyond 226 Hz – What's Different in Babies?".
  3. Community, Nature Portfolio Bioengineering (2022-06-15). "Computing for Audiology: Smartphone tympanometer for diagnosing middle ear disorders". Nature Portfolio Bioengineering Community. Retrieved 2022-06-19.
  4. "New mHealth tympanometer developed by Duke researchers could address preventable hearing loss in children". MEDx. 2022-04-19. Retrieved 2022-06-19.
  5. "Performing tympanometry using smartphones". tymp.cs.washington.edu. Retrieved 2022-06-19.
  6. Chan, Justin; Najafi, Ali; Baker, Mallory; Kinsman, Julie; Mancl, Lisa R.; Norton, Susan; Bly, Randall; Gollakota, Shyamnath (2022-06-16). "Performing tympanometry using smartphones". Communications Medicine. 2 (1): 57. doi:10.1038/s43856-022-00120-9. ISSN   2730-664X. PMC   9203539 . PMID   35721828.
  7. Greene, Alan (1 November 2008). "Ear Infections – The EarCheck Device". DrGreene.com.
  8. Teppo, Heikki; Revonta, Matti (2009). "Consumer acoustic reflectometry by parents in detecting middle-ear fluid among children undergoing tympanostomy". Scandinavian Journal of Primary Health Care. 27 (3): 167–171. doi: 10.1080/02813430903072165 . ISSN   0281-3432. PMC   3413189 . PMID   19565410.