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Bone Conduction Measurements on an Audiogram

During audiological testing the audiologist will want to find out whether the person has a hearing loss and how severe this may be and also what type of hearing loss it is. In general there are 3 types of hearing loss, including a conductive loss, a sensorineural loss or a mixed loss. Please visit SoundSpace Online - 1.2.2. Types of hearing loss for more information on this. Bone conduction testing is an important part of this investigation. 

In order to isolate what sounds the inner ear or cochlea is responding to, a set of sounds/beeps will be presented just to the cochlea, bypassing the outer and middle ear in a process referred to as bone conduction testing. A special headband with a bone vibrator is used and placed behind the worse ear, as measured by air conduction testing. It is held firmly onto the skull with the headband and a hearing test is then completed. During this testing, noise known as masking is played to the opposite ear, to make sure that the cochlea you are testing i.e. the worse cochlea is responding to the sounds being presented. The results of bone conduction testing are then represented on the audiogram. 

The results of air and bone conduction are then compared to find out what type of hearing loss is present: conductive, sensori-neural or mixed. For more explanations on the different hearing tests for these types of loss click on this NDCS video:

     

The British Association for Teachers of the Deaf (BATOD) has more detailed information about masking on this BATOD website pdf, and this online YouTube tutorial (above) takes you through an audiogram with bone conduction testing results.