Not everyone will benefit from a BCHD. A BCHD works best if a person hears better via bone conduction than air conduction, although there are some circumstances when an implantable device may still be considered.
When a patient has a hearing test, the audiologist will measure their hearing with headphones or earphones. This is measuring air conduction hearing. They will then also measure hearing with a bone conduction vibrator placed on the skull behind the ear.
If the patient hears at normal levels through the bone conductor but has a hearing loss when listening through the headphones this is called a conductive hearing loss, and usually indicates that there is a problem with sound being transmitted down the ear canal or through the eardrum and middle ear.
If the patient has a similar hearing loss when listening both through the bone conductor and the headphones this is called a sensorineural hearing loss and indicates that the problem is likely to be in the inner ear.
Often, a hearing test will show a hearing loss with both the bone conductor and the headphones, but with a difference in hearing levels between the two, which is referred to as a mixed hearing loss, where there may be both a problem within the ear canal/middle ear, and also in the inner ear.
A BCHD is most suitable for patients who have a conductive hearing loss or a mixed hearing loss, where hearing levels are better through the bone than through the ear canal.
BCHDs are also a suitable option for people who have no hearing in one ear and normal hearing in the other ear (usually referred to as single sided deafness, SSD). In this case, the BCHD would be placed behind the ear that doesn’t hear, and all vibrations from the device travel across the skull and are ‘heard’ in the good hearing ear. This enables people with a hearing loss on one side to be aware of sounds in their environment on the side that has no hearing.