Hearing Tests

Tests of hearing

  • Finger friction test ,Watch test, Speech test; whisper and conversational speech

  • Tuning fork tests

  • Pure-tone audiometry

  • Speech Audiometry

  • Impedance audiometry / tympanometry

  • Brain-stem evoked response audiometry

Finger friction test, watch test, clinical speech test and tuning fork tests are often used for hearing screening or bed side testing.

Tuning-forks test

256, 512 and 1024 Hz frequency, vibrating tuning forks are placed in front of ear (to test air conduction), behind the ear and over the forehead (to test bone conduction; here sound is directly transmitted to the cochlea) to get an idea of hearing, and degree & type of hearing impairment if any.

Surgical treatment (cauterization/paper patching/tympanoplasty)

If the eardrum does not heal, and the perforation is small, it can sometimes be closed by a simple office procedure like cauterization and paper patch..

Tympanoplasty is commonly performed for repair of the eardrum. The operating microscope helps to enlarge the view of the ear structures; a small patch from fascia (muscle sheath) is placed onto the eardrum.

If the bones of hearing are eroded, then ossicular reconstruction (ossiculoplasty) using artificial bones or ossicles from donor may be necessary at the time of tympanoplasty.

Pure-tone Audiometry

Audiometer is an electronic device which produces pure-tones.

Person has to put on headphones and then listen for some different tones from low pitch to high pitch. Person has to push a button or raise hand when he hears each tone.

Hearing is measured at different frequencies from (250 Hz to 8,000 Hz). Results in decibels are charted in the form of graph called audiogram.

This procedure is called Pure-tone Audiometry.

It is a subjective test of hearing and cooperation and understanding of patient is of utmost importance.

Audiometry is required

  1. To know degree and type of hearing loss.

  2. Before prescribing a hearing-aid.

Result interpretation; Reading Audiogram

  • ormal hearing: less than 15-20 decibels

  • Minimal loss: 16 to 25 decibel loss

  • Mild loss: 26-40 decibel loss

  • Moderate loss: 41-55 decibel loss

  • Moderately severe Loss – 56 to 70 decibel loss

  • Severe loss: 71 to 90 decibel loss

  • Profound: 91 decibel loss and above

To know the type of hearing loss bone conduction is tested, If hearing is better by bone conduction a conductive loss is present.

Normal Adudiogram

Speech audiometry

In speech audiometry a patient’s ability to hear and understand speech is measured.

Speech reception threshold is minimum intensity at which a person is able to repeat at least 50% of words correctly. Here a set of two syllable words with equal stress on each syllable (spondee words) are used.

Speech discrimination score is percentage of words heard correctly when phonetically balanced words at 30 to 40 decibel above the person’s hearing threshold are presented.

A score of 90 – 100% is considered excellent, 80 – 89% is good, 70 – 79% is fair, 60 – 69% is poor, <50% is considered very poor.

Tympanometry or Impedance audiometry

Objective test of hearing; particularly useful to test hearing in infant and child, to know patency of Eustachian tube, and to know condition of middle ear like presence of fluid or fixation (as in otosclerosis) or dislocation of ossicles.
Ossicles are 3 small bones present in middle ear namely malleus, incus and stapes.

Tymanometry is the dynamic measurement of middle ear pressure through measuring mobility of the tympanic membrane. The resultant changes in air pressure variation are plotted on a graph called tympanogram.

Acoustic reflex testing consists of response contraction of subjecting the ear to a loud sound a rough method of evaluating hearing.

Interpretation of tympanogram

The shape of the tympanogram suggests how the eardrum is functioning.

Normal eardrum movement is shows a well-formed peak, where height of the peak indicates the amount of eardrum compliance.

A flat line indicates little or no eardrum movement. This type of tympanogram is commonly seen when fluid is present behind the eardrum or when there is a hole or perforation in the eardrum.

A peak to the left of the normal pressure range means adequate eardrum movement with negative middle ear pressure, seen in persistent cold or initial phase of fluid accumulation or recovery phase of fluid accumulation.

Interpretation of tympanogram

Brain stem evoked response audiometry (BERA)

Auditory brain stem response (ABR) audiometry, Brainstem auditory evoked response audiometry (BAER).

It is a test of neurological activity of auditory brain stem in response to auditory stimuli (sound presented to the ear) It is an effective screening tool for evaluating cases of deafness due to retro cochlear pathology i.e. (Acoustic schwannoma) and is used to test hearing in newborn and children.

Otoacoustic emissions

It is used to determine cochlear function and assess hearing in newborns.

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