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.
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.