Open Hearing Aid--The Sole Secret Book for Dealing with Ear Blockage
What does an open fit digital hearing aid look like?There are two main types of open fit digital hearing aids. One is transparent hollow microphone and open earplug, which is commonly called open acoustic tube hearing aids. The other is the thin-wire sound tube + microphone + open earplug, which is what we call RIC hearing aid. One notable feature of these two kinds of open hearing aids is the use of "open earplugs", which can effectively eliminate the effect of ear plugging and make them more comfortable to wear without feeling of oppression and blockage.
When the ear canal is open without hearing aids, the sound will change in the process of transmission through the external auditory canal to the tympanic membrane, resulting in resonance, which will increase the sound by 20 dB-30 dB.
So how can open fit digital hearing aids solve the problem of ear plugging?
In addition, when speaking, it is mainly through the bone conduction pathway, that is, the voice of the speaker directly vibrates the head (skull), across the outer and middle ears, and directly to the inner ear. Bone conduction increases the low frequency of your voice, which is difficult to detect in the open state of the ear canal.
However, when the hearing aid is put on and the ear canal is blocked, the "resonance" above and the "low-frequency enhancement of the voice of one's own voice" will be changed, and the resonance will be weakened, and the low-frequency enhancement will be obvious. As a result, hearing aids users feel that their voice sounds hollow, especially when they speak, chew and swallow, that is, "enhanced self-hearing".
This sense of ear plugging is just like that of a normal listener who plugs his ear with his finger and speaks on his own. Obviously, he feels his voice is louder and his ears are shaking.
The open fit digital hearing aids, from hollow microphonic tubes to open earplugs, have greatly maintained the natural open state of the ear canal. As can be seen from the green curve of the open sound tube in the figure above, there is no additional gain in the low frequency part, which is close to 0 dB.
In addition, the open fit digital hearing aids hardly change the natural auditory canal resonance (see figure below, wearing and not wearing open hearing aids, the low-frequency part is no different), low-frequency signals can be released, avoiding vibration and boredom. It also allows sound to enter the ear canal through an open earplug, allowing better low-frequency ears to listen directly.
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