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What is BTE hearing aids?
Behind-the-ear (BTE) hearing aids are main accessories are installed in a crescent-shaped housing and worn behind the ear. They are the preferred type of hearing aids for children.
Basic structure of BTE hearing aids
The body shape of the behind-the-ear hearing aid is banana-shaped, about 3 to 4 cm in length. The microphone, amplifier, receiver, and battery are all assembled in the body. There are various sound processing circuits in the higher-grade hearing-ear hearing aid. The upper end of the hearing aid is a sound-seeking earhook that bends into a semi-circular shape. This sound-guiding earhook connects the hearing aid to the ear mold and can be fixed behind the auricle. The amplified sound is transmitted to the sound hole of the ear mold through the ear hook and the plastic tube. There are switches, volume regulators, tone adjustment files, maximum sound output adjustment files, and T files on the back-of-the-ear hearing aid housing of some analog circuits. Many BTE hearing aids work with external devices
Connected use, such as wireless FM or infrared language training system.
1- ear hook 2 a receiver 3- microphone 4- volume control potentiometer
5- trimmer potentiometer 6-amplifier 7-switch 8-battery compartment
1. Ear hook for BTE hearing aids
The ear hooks of the hearing aids are all in the shape of a crescent, the main function of which is to make a part of the sound system of the hearing aid, and to connect with the ear mold of the hearing aid to fix the hearing aid. Ear hooks are common type, child type, windproof type, metal type, frame type and so on.
(1) Ordinary ear hook
Common ear hooks are mostly curved hollow plastic hooks with a length of 25 to 35 mm. The thick end is connected to the sound tube of the hearing aid receiver, and the thin end is connected to the hearing aid ear mold system. A metal ring is usually used to fix the ear hook near the fuselage, but this metal ring is more likely to be damaged due to the corrosion of sweat. In addition, the front end of the ear hook is thin, and it is easy to break if it is often removed from the ear mold. If the earhook is damaged, it can be replaced by professionals or users, but it should be noted that the earhook should be replaced with the original earhook model as much as possible. At the same time, the new earhook should be gripped when transferring the earphone of the hearing aid receiver. Tighten the case of the hearing aid to prevent the case from breaking.
(2) Child-type ear hook
The length of children’s earhook is slightly shorter than that of ordinary earhook, and the curvature of earhook is more obvious than that of ordinary type. Children use this earhook to fix the hearing aid on the auricle more closely. There are also hearing aids produced by the company, which have size ear hooks, which are suitable for children.
Suitable for children of different ages, increasing the comfort and aesthetics of wearing.
(3) Wind-proof ear hook
Windproof earhook is a more common hearing aid earhook. Its main function is to reduce the impact of wind noise. It is mainly by widening the upper part of the earhook near the sound tube, and on the microphone of the hearing aid. A windproof device that enables the user of the hearing aid to reduce the effects of wind noise on him while riding a bicycle or in a car. It is especially effective for the environment where some users are outdoors affected by wind noise.
(4) metal ear hook
Metal type ear hooks are also a new type of ear hooks that have appeared in recent years. Its main function is to meet the needs of high volume hearing aids in recent years. These high-power hearing aids must be designed to be small and exquisite, and the power must be large enough. This requires that the receiver of the hearing aid be placed as far away from the upper microphone as possible, so that the distance between the hearing hole of the hearing aid receiver and the ear hook is extended. In the past, this distance of the hearing aid was connected by a tubular rubber piece. However, if the distance is extended and the amplification power of the hearing aid is large, the rubber piece is more likely to generate vibration and make the hearing aid whine. Therefore, connecting a metal long ear hook from the sound hole of the hearing aid’s receiver can not only play the role of ear hook sound transmission and connect the ear mold to fix the hearing aid, but more importantly, the volume of the hearing aid using the metal ear hook can be The smaller the power, the more power can be made.
(5) Frame type ear hook
The frame-type earhook is a device for fixing a protrusion on the spectacle frame to the ordinary earhook, so that the eye-wearer can more easily fix the hearing aid and glasses without falling off when using the hearing aid.
2. shell of BTE hearing aids
The hearing aid housing has changed a lot in recent years. The first is that the shape is more beautiful and exquisite, especially for hearing aids of small and medium power, this change is even more obvious. Secondly, there are two different development directions in the color of the case. First, the color of the case is more concealed. For example, the ear-hearing hearing aid with yellow skin color or black shell is more suitable for yellow or black people. , While the black-haired person uses the back of the black case, which has better concealment; the second is to develop personally, and it is eye-catching and eye-catching. The usual colors are orange, sky blue, red, etc. Hearing aids are designed to cater to some individuals with a personality and a challenging spirit. This can attract more people’s attention and remind the other party to pay attention to the way of talking with the person wearing the hearing aid in front of them to help them communicate better and attract them. For those children who like to use the colorful hearing aids as accessories.
The shell of the behind-the-ear hearing aid has undergone some changes in recent years, such as the use of a double shell. The advantage of this double shell is that it can effectively improve the drop resistance of the hearing aid, which is more suitable for children. In addition, some hearing aid companies are also committed to the development of waterproof ear-hearing hearing aids with better casing sealing, and have been launched in recent years.
The inner wall of the shell of some behind-the-ear hearing aids is coated with a silver electromagnetic wave barrier protective coating, which can shield the electromagnetic waves from interfering with the hearing aid. There are various electromagnetic waves in modern life, such as household appliances, fluorescent lamps, mobile phones, etc., which will emit various electromagnetic waves, which will cause electromagnetic signal interference to hearing aids, which will sometimes seriously affect the use of hearing aids.
3． microphone of hearing aids
The microphone of the behind-the-ear hearing aid is also a part of the hearing aid that has developed and changed greatly in recent years. The earphones of the ordinary ear-ear hearing aids are placed at the bottom of the hearing aid, and the position of this microphone is opened. The distance to the hearing aid receiver reduces the occurrence of howling hearing aids. The precision of the hearing aid design is not very high, so the price of this type of hearing aid is relatively cheap, but because the microphone position of this type of hearing aid is not in front of the hearing aid, In terms of the directionality and sensitivity of the received sound, the effect is worse, so in the late 1990s, few manufacturers produced such hearing aids.
The development of the behind-the-ear hearing aid microphone is reflected in the changes in the external design of the microphone. First, a metal or plastic mesh cover is installed outside the microphone to prevent dust from entering the hearing aid microphone.
After the 1990s, the development of microphones was based on the directivity of the microphone. This directional microphone will greatly facilitate the hearing-impaired hearing aid users to listen better in noisy environments, and eliminate the impact of ambient noise. To hear sound interference, this type of hearing aid is particularly suitable for users who need to listen to the voice of the main speaker while effectively negating the sound signals that they do not want to hear. However, the shortcoming of this type of directional single microphone hearing aid is that if the user wants to hear the speaker more clearly, he must face the hearing aid directly.
In the mid-to-late 1990s, the directional microphones of BTE hearing aids developed towards the direction of dual sound inlets. This microphone has two sound inlets, one facing forward and one rear, respectively. The vibrating diaphragm inside the microphone feels both directions. The sound of the sound is converted into the corresponding electric signal output, and an acoustic delay filter is provided at the rear sound entrance to suppress the intensity of the sound signal from the back of the human ear and optimize the useful signal from the front. This is fully consistent with the auditory effects of normal human ears. The auricle structure of our human ears also collects sounds forward, while blocking (attenuating) sounds from the back of the human ears. These sounds are usually background noise or irrelevant talk.
It can be seen from Figure 3-6 that the listening range of the directional microphone is concentrated on the front and sides of the person, and the sound from the back is cut down, which can make the wearer focus more on talking with people. In addition, some foreign hearing aid research surveys have shown that BTE hearing aids with directional microphones are also significantly better than traditional BTE hearing aids. This is more advantageous for users who use hearing aids on one side. In China, where the majority of hearing aids are used on one side, the advantages of this directional microphone are even more obvious.
This design idea of directional microphone is mainly used to reduce the environmental noise of hearing aids. When a user wears a directional microphone hearing aid, the directional microphone mainly collects sounds from the front, and at the same time reduces the intensity of the background noise by a corresponding proportion. However, it was soon discovered that the effect of directional microphones is greatly affected by factors such as aging of the microphones, thereby reducing its noise reduction function. This is because after the hearing aid is used for a period of time, some small parts are loose, wet, secretions from the ear canal skin or other foreign matter will affect the performance of the microphone. Hearing aids with dual microphones usually have good directional functions immediately after purchase or repair , But with the use of time, its directional function will gradually weaken. Studies have shown that if the two microphones differ by ldB, hearing aid users can reduce speech intelligibility by IO%. However, with the development of digital technology in recent years, the emergence of dynamic microphone matching technology has brought the era of true dual microphones.
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