One of the first comments that new hearing aid wearers have when first being fit with hearing aids is, "why does my voice sound so different?". Well, there are two possible answers to this question. It is either your own voice being amplified by your new hearing aids, or you are experiencing the Occlusion Effect.
Let's discuss the first culprit. There is a solid chance that you haven't heard your own voice in a long time. Hearing aids are primarily designed to amplify speech. Due to this, it is highly likely that your own voice will also be amplified to a higher level. This results in your own voice becoming abnormally loud compared to what you are accustomed to. Fortunately, this is something that new hearing aid users tend to adjust to pretty quickly.
However, the second culprit, the Occlusion Effect, is often a different story. The Occlusion Effect occurs when the sound of your own voice, or the sound of you chewing on food, is bone conducted through your jaw and skull. This vibration of sound eventually ends up in your ear canals. Typically, this vibration would escape your canals, but if it cannot escape due to the use of a hearing aid or ear mold, it will vibrate your eardrums causing your voice to become loud to yourself. Some people describe this as a Hollow Sound, a Loud Booming Sound, like your are Talking in a Barrel, or Talking in a Tunnel.
It is generally east to determine which one you have by either performing an objective measurement using Probe Microphone Measurements, which are also used for Real Ear Measurement, or by muting your hearing aids and having you talk to see if the booming perception goes away or remains. If this perception remains, you have the Occlusion Effect.
The Occlusion Effect is typically experienced more often by individuals who have Really good Low-Frequency Hearing thresholds. This is because the Occlusion effect is perceived at frequencies below 500 Hz. The better you hear sounds below 500 Hz, the more you will perceive Occlusion. On the other hand, if you have bad hearing in the frequencies below 500 Hz, then you are unlikely to experience the Occlusion Effect.
So, if you have the Occlusion effect, is there a way to eliminate or reduce it? The answer is Yes! There are two ways to reduce the perception of the Occlusion Effect. First is to increase the venting of your ear mold or use an open dome. This will allow for the bone conducted sound in your ear canal to escape. The bigger the vent, the less risk you have of experiencing Occlusion. Second, is to have a deeper inserted ear mold or hearing aid. The less space between your eardrum and the tip of your hearing aid or ear mold, the less space that your voice has to vibrate, reducing occlusion as well.
Seems simple right? Wrong. The larger you make a vent, the more risk you have of allowing amplified sound to leak out and cause feedback or whistling. The deeper you go inside of an ear canal, the more sensitive it becomes so inserting a hearing aid or ear mold too deep could cause comfort issues. That being said, if your hearing care professional is good at what they do, they will be able to find the right balance between an acceptable amount of Occlusion, and an appropriate amount of Amplification at the same time.