The sound tube of the hearing aid is a commonly used component of the hearing aid, and also an important component that affects the acoustic characteristics of the hearing aid. The sound tube of a hearing aid generally refers to two uses: one is used inside various customized hearing aids, where it is connected to the speaker, which is not easy to find from the outside, and the other is a pipe that connects the ear mold channel port and the hearing aid ear hook. Therefore, in hearing aids, we mainly refer to this sound tube, of course, part of the acoustic principle of the custom machine's sound tube is also the same.

The hearing aid sound tube is a small plastic pipe used to connect the hearing aid ear mold, and the sound is passed from the ear hook of the hearing aid through the ear mold, and then into the ear. The sound tube must have good softness and closeness. At present, some places still use hard plastic pipes to replace special hearing aid sound tubes. Not only are the sizes not standardized, but the materials and materials are not suitable, they are easy to age.

The inner and outer diameters of the sound tube are different, and the thickness and length of the tube wall are also different. These differences are just the main factors that affect the sound transmission of the hearing aid. In fact, in foreign countries, these basic parameters of sound tubes have been standardized as early as 1979. For example, the National Association of Ear Model Laboratories stipulates that various sound tubes used for hearing aids are divided into different specifications from 9 to 16 according to their diameters. Generally speaking, the smaller the number, the larger the inner and outer diameters. For example, the inner diameter of sound tube No. 9 is 3 mm, while the inner diameter of sound tube No. 16 is only 1.35 mm. Commonly used sound tube models are the 13th standard type and the thickened type, deaf education. The inner diameter of these two models is the same: both are 1.93 mm, but the outer diameter is different. The outer diameter of the thickened type is slightly larger than the standard type by 0.35 mm. From the analysis of acoustic effects, the reason why the No. 13 sound tube is widely used is mainly because of its smooth sound transmission effect and excellent sound effect. For example, the peak of the No. 13 sound tube is generally around 1000 Hz, and the larger the diameter of the sound tube, the greater the peak value affects the higher frequency. On the contrary, the peak of the smaller diameter sound tube is added at low frequency, the second case It may affect the quality of the sound and react differently to the external sound. For example, the peak may amplify the low-frequency noise too much at low frequencies, and the peak may cause unnecessary howling at too high frequencies.

We often use sound tubes with small diameters to deal with power saturation, such as reducing gain. Therefore, the diameter of the sound tube cannot be increased or reduced at will. The smaller the inner diameter, the closer the peak frequency of the frequency is to low frequency; otherwise, the closer it is to high frequency. The length of the sound tube itself also has a certain influence. The shorter the sound tube, the higher the peak wave of frequency amplification.

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