Bone conduction systems are designed for people with conductive or mixed hearing loss, or single-sided deafness.  They work by utilizing our body’s natural ability to conduct sound.  There are two ways we hear sound: through air conduction and through bone conduction.  Bone conduction systems were developed for people with conductive and mixed hearing loss, or single-sided deafness, to bypass air conduction hearing utilizing the patient’s better bone conduction hearing. There are two types of bone conduction systems as of 2015:

  • Bone conduction processor with abutment
  • Bone conduction processor with magnet system

Both systems have an implanted titanium post placed behind the ear in the mastoid bone, and then use an abutment or magnet to obtain sound from an external speech processor.

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Bone Conduction Abutment System: The bone conduction abutment/implant system consists of three components: the titanium fixture or post, the abutment, and the external sound processor.

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Small Titanium Implant

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Abutment without Sound Processor

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Sound Processor on the Abutment

The external sound processor takes in acoustic sound and translates the signal into vibrations. Those vibrations are sent, via the implant and abutment, through the skull to a functioning inner ear rather than through problems in the outer and/or middle ear – a process known as direct bone conduction.

A bone conduction system is an auditory osseointegrated implant system, which is an alternative hearing instrument for those who can benefit when there is no other suitable aid. The device, originally called the Bone Anchored Hearing Aid (Baha), is implanted in the temporal bone behind the ear and actually fuses (osseointegrates) with bone behind the ear to provide transmission of sound via direct bone conduction. Patients with conductive or mixed hearing loss, or single-sided deafness benefit from this device. The Baha device will help users localize sounds and improve hearing in competitive noise situations to a varying degree dependent upon the degree of underlying hearing loss. The Baha implant has been used successfully for more than 30 years and has become a treatment of choice for tens of thousands of hearing impaired people worldwide.

Bone Conduction Magnet System: Much like the bone conduction system with abutment, in the bone conduction magnet system sound is translated into vibrations by the external speech processor. A magnet is attached to the external processor. The vibrations are then transmitted from the external sound processor and magnet to the internal magnet, then to the titanium implant. Sounds are then delivered to the functioning inner ear. This option leaves the patient without any abutment, but requires less hearing loss to be present.

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There are three main types of hearing loss: sensorineural hearing loss, conductive hearing loss, and a combination of the two referred to as mixed hearing loss.

Sensorineural hearing loss means that there is a problem in the inner ear (cochlea) or auditory nerve. A bone conduction device may not be the best solution for you, unless you have single-sided deafness (deafness in one ear and normal hearing in the other ear), or there is a reason that you may not wear a conventional hearing aid.

If you are deaf in one ear, also referred to as single-sided deafness (SSD), a bone anchored hearing system may be the most appropriate solution. Being deaf on one side reduces not only your ability to locate sounds but also your ability to follow conversations in noisy environments – a combination that can make everyday life quite challenging. Traffic situations, such as biking and jogging, and noisy situations such as meetings and social gatherings can be particularly problematic if you are deaf in one ear. A bone anchored hearing system can pick up sounds on your deaf side, convert them into sound vibrations and transfer them to your healthy ear via the skull bone. By reducing the head shadow effect and making it easier to understand speech, bone anchored hearing systems can take much of the work out of listening.

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Sensorineural Hearing Loss

Conductive hearing loss happens when an obstacle somewhere in the outer and/or middle ear stops sound from reaching your inner ear at an audible volume. Conductive hearing loss is often caused by chronic ear infections. These can be aggravated by conventional hearing aids as they physically block the ear canal, which increases the risk of irritation and infection. With a bone anchored device, these problems can be reduced or avoided, as the ear canal is always open. Another common cause of conductive or mixed hearing loss is atresia, a malformation of the outer ear where the ear canal is either missing or very narrow. By transmitting the sound directly to the inner ear via the skull bone, without it having to pass through the ear canal and middle ear, sounds completely bypass these obstacles allowing for better hearing and speech understanding.

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Conductive Hearing Loss

Mixed hearing loss is a combination of sensorineural and conductive hearing loss. Much like with conductive hearing loss, a bone conduction device concentrates on compensating for the sensorineural hearing loss by amplifying sounds without having to first break through the ‘road block’ in the ear canal or middle ear. The result is clearer, more natural sound quality.

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Mixed Hearing Loss

Bone conduction systems are available for up to moderately severe conductive or mixed hearing losses. Possible Baha candidates may have hearing loss from:

  • Malformation of the ear canal or middle ear
  • Chronic ear infections (outer or middle ear)
  • Congenital atresia
  • Cholesteatoma
  • Middle ear dysfunction/disease
  • Sudden hearing loss
  • Acoustic neuroma
  • Meniere’s disease

Children may also be candidates for bone conduction devices. For children with hearing loss to successfully develop language skills, early stimulation of the inner ear (cochlea) is essential. A softband is ideal for children who are either too young to have an implant, or whose hearing problems are temporary. Wearing the sound processor on a softband, rather than on an abutment, is also a good way to evaluate how much the sound processor is helping your child, before deciding to have an implant placed. Softbands are elastic and adjustable, fitting any head size- even infants. The softband can also be moved to the optimal position for comfort and hearing. Children who need a processor on both sides can get a special softband for that as well.

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A comprehensive evaluation, including in depth audiological testing and medical evaluations by our team, needs to be completed to determine if a bone conduction system is right for your hearing needs. The medical evaluation usually includes review of audiological test results, physical examination, tests performed by the surgeon, CT scan, and counseling to ensure suitability of a bone conduction system. The audiological evaluation consists of diagnostic testing, including an opportunity to try the Baha processor connected to a soft headband during your appointment. This will provide some sense of what sound would be like when delivered through bone conduction.
The surgical procedure to have a bone anchored implant placed is safe and simple. Generally, the surgery is quick and done as an outpatient procedure. There is no risk of damage to your ear or your hearing during this surgery. A titanium post implant is implanted into the bone (mastoid) behind your ear. In most cases it takes no more than a day or two away from work or school to recover. After 10-14 days, when the skin has healed, you will be able to have the dressing and stitches removed. You won’t be able to attach the sound processor until the implant has fully merged with the bone. This process, called osseointegration, normally takes about three months from the surgical procedure. Your doctor will teach you how to keep the abutment area clean. If the patient is a child, or the bone is thin or soft, this process can take longer. Your surgeon will let you know when the implant is stable enough to receive the sound processor.
The final step in the treatment process is to have your sound processor customized to meet your personal needs and preferences. Once you have been medically cleared by your surgeon, you will then see your audiologist. Your audiologist will fit and program the external sound processor. Regular hearing evaluations and programming of your external sound processor are recommended.

Images provided by Cochlear and Oticon Medical