What is a Bone Conduction Test?
A bone conduction test is very similar to a pure-tone test in that pure tones are presented to the patient and the patient responds when they hear the tone. However, there is a major difference in how the sound is delivered and heard by the patient in a bone conduction test. This test, along with the pure-tone test, helps the hearing health professional properly diagnose and treat the type of hearing loss that may be present in a patient.
How is it performed?
A bone conduction test is performed by placing a headband on the patient. The headband has a small square-like box that is placed behind the patient’s ear. This is an oscillator and this is how the sound is presented to the patient. The oscillator vibrates and sends the pure-tone sound directly into the cochlea, bypassing the outer and middle ear. This test is important in helping to determine if there is a problem with the outer ear, such as the ear canal, or the middle ear, such as the eardrum or the bones of the middle ear.
The patient is once again seated inside of the sound booth to ensure no outside noise interferes with the testing to ensure accurate test results. The hearing health professional then delivers the same type of pure tones to the patient and the patient is instructed again to put up a hand or to press a button when the tone is heard. The hearing health professional delivers the pure tones at the same frequencies as the pure-tone test to ensure accuracy between the two tests and congruency between the tests as well.
The patient is tested in each ear to ensure accuracy because one ear may be worse than the other. Masking may be performed with bone conduction testing because the ear not being tested picks up the tone. When masking is performed with bone conduction testing the headphones or earbuds are placed on the patient and the non-testing ear is given a white noise to mask it from hearing the pure tone that is being given and tested to the other ear.
Bone conduction testing is important in helping to determine the type of hearing loss that a patient may have. If the test results from the pure-tone test and bone conduction are the same or very close then a sensorineural hearing loss is present, however, if the test results from both tests are far apart then a conductive hearing loss may be present and further investigation as to what is causing this type of hearing loss needs to be done.