What is bone conduction hearing aid

Yesterday, a patient with hearing loss asked to wear a bone conduction hearing aid when consulting. This situation is not common, so I asked him, “why do you think that bone conduction hearing aid? Do you know it?” the other party shook his head and said, “this is introduced by my friend, who said that it can be worn very well.” So I started to introduce bone conduction hearing aids to him: not for everyone.

Style of bone guide hearing aid

In the professional hearing aid fitting center, the common hearing aid styles are: ear back type and inner ear type, but these are all air guided hearing aids. Are bone conduction hearing aids the same as air conduction hearing aids? In fact, they are different.

The common styles of bone guided hearing aids are: spectacle type, collapsing band type and head clip type. This kind of machine is non-surgical and can be selected in some hearing aid fitting centers.

Bone conduction sound

Generally, the sound we hear in the human ear is collected through the auricle, transmitted through the outer and middle ear, finally felt by the inner ear, and then transmitted to the auditory cortex through the auditory nerve, so as to produce hearing. How does bone conduction make us hear sound?

Bone conduction hearing aid amplifies the collected sound, converts it into electrical signals, and converts these electrical signals into mechanical energy, directly vibrates the skull, the skull transmits the vibration to the cochlea, and finally the inner cochlea senses the sound, which is transmitted to the auditory cortex through the auditory nerve, and the sound is heard by us. The transmission of sound does not need to pass through the auricle, the external auditory canal and the middle ear, which is an important difference from air conduction.

Wearing position

Because of different styles, the air guide hearing aid is hung on the back of the auricle, or the whole machine is inserted into the outer ear canal. The wearing method is simple, easy to use, with good concealment and comfort.

The vibrator of bone guided hearing aid must be close to the skull and press vertically on the surface of skull. It is usually placed on the mastoid or other parts of skull; it does not need to contact with auricle or external auditory canal; it has poor concealment and comfort.

Some shortcomings

Just like air guided hearing aids, bone guided hearing aids have a design life of 5-8 years and can be used for a long time. However, the long-term use of bone conduction hearing aid will make the skin hard and the contact parts painful; for frequencies above 3000-4000hz, the amplification effect provided by it is very small (while the air conduction hearing aid can amplify frequencies within 125-10000hz, with a wider bandwidth).

Because of its poor sound source positioning, small sound output, narrow frequency range, more distortion, inconvenient to wear, uncomfortable and other shortcomings, it is rarely used in clinical; it is also not common in matching center.

Special bone conduction hearing aid

Bone fixation hearing aid (BAHA) is a special type of bone guided hearing aid. It also transmits sound by vibrating the skull. The difference is that it needs to implant titanium ingot in the mastoid through surgery. After fixation, it is connected with a vibrator to transmit vibration to the skull so that people can hear the sound. It will not produce skin hardening and tenderness. It is more comfortable to wear and more beautiful.

In some countries, BAHA has largely replaced the traditional non-surgical hearing aids. If you want to have a good sound source localization, you can implant BAHA in bilateral surgery, and increase the speech intelligibility under the noise environment, so the listening effect is better. – these bone conduction hearing aids are not available in the fitting center, and can only be used in hospitals through surgical implantation.

Who can use bone conduction hearing aids

Bone conduction hearing aids are generally used in patients with conductive hearing loss, congenital external ear hypoplasia (such as atresia, stenosis, etc., or ear deformity), and some patients who are not suitable for wearing air conduction hearing aids due to external ear, middle ear disease (such as chronic suppurative otitis media, long-term anti suppurative).

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Tip:

1. The power of the traditional non-surgical bone conduction hearing aid: the average value of the bone conduction is less than or equal to 55 dB HL; the wearing effect will be affected by the thickness of the skull, the thickness of the fat under the scalp and the wearing position.

2. Power of surgical implanted BAHA: the average value of bone conduction is less than or equal to 65 dB HL; this kind of hearing aid has a wound outside the skull, so we need to pay more attention to hygiene and dryness in daily life to prevent infection.

Jinghao hearing aid reminder: hearing aid wearing requires professional “matching”, so it is very important to choose a professional hearing aid matching center and a hearing aid tester! If you have any hearing problems, you can call Jinghao for consultation, or come to the matching center for experience. Hearing aid free consultation Tel.: + 86-18566295705