The unnaturalness of your own voice or the sound of chewing as well as the feeling of the ear being blocked or plugged up can be a real challenge for some people wearing hearing aids. Called the occlusion effect, it is caused by the ear canal being either totally or partially blocked by either the hearing aid itself or an ear mould or plastic ear dome, depending on the hearing aid. Normally when we speak, the bones in our skull vibrate and some of these vibrations escape through the ear canals. However, when the ear canal has something blocking it, the vibrations get trapped between the obstruction and the ear drum resulting in the amplification of a wearer’s own voice, especially in the lower frequency tones. People with good low frequency hearing can be especially prone to the occlusion effect, particularly men with deeper, resonant voices. As there are several solutions that could help your problem depending on your particular hearing condition, I strongly recommend you discuss your concerns with your audiologist. Typically there are three recommended solutions that could possibly reduce or eliminate the occlusion effect.

1. Venting:
The creation or modification of an air vent in an in-the-ear hearing aid or the ear mould of a behind-the-ear hearing aid may help. An air vent running through the hearing aid or mould allows air trapped between the device and the ear drum to escape helping to reduce the amount of trapped vibration from the wearer’s voice and the consequent unnaturalness of the sound. Wider, shorter vents are typically more effective. However, the use of an air vent and its width is highly dependent on the level of your hearing loss and which frequencies (pitches) of sound are affected. For good low frequency hearing and high frequency hearing in the moderate range, a wider, shorter vent may be a good option. But for a severe hearing loss across the whole pitch range there may not be much flexibility venting-wise because the wearer cannot afford to lose some of the amplified sound that will invariably also escape through the vent. A wider vent could also lead to feedback, the whistling sound that is caused by amplified sound feeding into the hearing aid microphone and being re-amplified. This is more likely to occur when there is a wider vent and/or if high levels of amplification are required. Some feedback cancellation systems in hearing aids help to reduce the occurrence and severity of feedback, which allows more flexibility with larger vents. The width of the vent also has to be limited in some cases because of the size of a person’s ear canal. For people with narrower ear canals there may not be much space to create a larger vent. Open fit hearing aids can be a good solution for people with good low frequency hearing and a hearing loss predominantly in the higher frequencies. These comprise of a behind-the-ear hearing aid with a thin tube receiver attached to an ear dome that sits within the ear canal. The dome (or tip) is made of a soft pliable material so it can accommodate larger vents. But this style of hearing aid does not suit all types of hearing losses due to the reduction of amplification in some frequencies that can occur and the reduced effectiveness of directional microphones and audibility in background noise. Unfortunately with hearing aid fittings there can be a compromise between comfort and clarity. Research has found that hearing aid non-usage rates have decreased from 23% in 2006 to 13% in 2012 and attribute some of this success to the use of open-fit and thin-tube hearing aids.

2. ITC models:
Sometimes a deeper-fitting completely in-the-canal hearing aid can help with the occlusion effect by reducing the space between the hearing aid and the ear drum. However, these deeper fitting aids are not recommended for everyone and can only be fitted for certain hearing loss configurations. Also, some wearers can find the deeper sitting aids uncomfortable to wear.

3. Setting adjustments:
Sometimes changing the amplification in some frequencies can improve the quality of the wearer’s own voice so it is worth discussing this with your audiologist. In some cases, unfortunately even with your audiologist’s best efforts, the occlusion effect can still be present. Often the benefits of amplified hearing delivered by hearing aids eventually outweigh the negative by-product of having a blocked ear canal. 

Stapedectomy surgery for a conductive or mixed hearing loss due to otosclerosis usually has wonderful results. The hearing threshold is improved and the quality of sound is very natural. However it does carry risk of a dead ear, which occurs in 0.5-1.0% of surgeries despite the surgery being carried out competently. In

this situation it would leave only one hearing ear on the opposite side. In such a situation it would be strongly advisable not to undergo surgery on the opposite side because of the small risk of a second dead ear. Fortunately there are several options for rehabilitating hearing in this situation with hearing aids of various kinds. A bone anchored hearing aid (BAHA) is one such device which can help. It is placed under the skin in the mastoid bone behind the ear and works by bypassing the middle ear and stimulating the cochlea directly through the bone of the skull. BAHAs have predictable hearing outcomes in conductive hearing losses. This hearing result can be experienced by a trial simulation of the BAHA before undergoing surgery to implant the device. The surgery to implant a BAHA is simple and carries no risk to the underlying hearing. An external speech processor held on by a magnet or small clip generates sound vibration to be transmitted to the implant under the skin.

There are several other kinds of middle ear devices which can also be used in this situation. A device which has recently become available in Australia is the Bonebridge. This is an active middle ear implant which has the source producing the sound vibrations implanted within the mastoid bone behind the ear, rather than externally in the speech processor as with the BAHA. Many other implantable devices which can help are also being investigated. Some are active devices that attach to the middle ear bones such as the Vibrant sound bridge. However these devices require more complex surgery than the Bone Bridge or BAHA for placement. They also required manipulation of the middle ear bones, and hence carry a risk to the underlying hearing. These devices would not be suitable for surgery on the side of an only hearing ear. 

Otosclerosis is a hereditary disease which results in progressive stiffness of the stapes bone, the third of the three middle ear bones. As the stapes bone becomes progressively stiff it transmits sound energy less efficiently through the middle ear resulting in conductive hearing loss. What is so exciting about otosclerosis is that the middle ear component of the hearing loss is treatable by surgery generally called stapedectomy. The principle of this operation is to restore sound transmission to the inner ear bypassing the fixed stapes bone. This can be achieved either by removing the entire stapes bone (stapedectomy) or drilling a very fine hole through it (stapedotomy) and replacing it with an artificial stapes bone. When stapes operations were first developed in the 1950s, it was necessary to remove the whole stapes bone before introducing an artificial stapes replacement (generally made of fine stainless steel wire and fat taken from the ear lobe).

As the micro drills, and more recently lasers, were developed it became possible to drill a fine hole (less than 1 mm in diameter) through the stapes footplate and introduce a replacement stapes bone (made of titanium/ platinum and Teflon) to effectively bypass the fixed bone, leaving the remaining footplate largely intact. Both operations in skilled hands produced wonderful hearing results, and both operations still carry similar risks of permanent and severe hearing loss (dead ear, less than 0.5%). However, the stapedotomy operation produces less trauma to the inner ear, preserving the higher hearing frequencies. The modern stapedotomy replacement bones are also safer to revise if necessary and the replacement prosthesis is compatible with MRI (magnetic resonance imaging) scanners if imaging of the region is required later on. Because of these advantages, all modern stapes surgery for otosclerotic hearing loss is in the form of stapedotomy. 

The mobile phone with the inbuilt telecoil is the Oricom EZY100. It also has a +25dB volume boost. I’ve had some implant patients who love the phone and others who haven’t had the best result, so it would be good if they could trial the system before purchasing or have assurance by Oricom that they can return it if not happy. Alternatively, your clinic could become a distributor in which case it would be worth having a demonstration phone on hand that clients can trial before they purchase from you. I’ve found the whole range of Oricom phones very useful but on the odd occasion some people haven’t had much success with them and so the ability to return it or have a trial before purchase is really useful.

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