Disadvantages of hearing aid microphones

The main disadvantage of the microphone is that it will eventually be damaged if exposed to unfavorable chemicals (such as sweat)

What's less of a concern is that all electronic components produce a small amount of random electrical noise, and microphones are no exception. Noise can cause irregular movement of air molecules relative to the diaphragm, and can also cause irregular electrical movement inside the microphone amplifier. After this kind of noise is sufficiently amplified by the hearing aid amplifier, it can sometimes be heard by hearing aid users in a quiet environment, especially users whose hearing is close to normal at certain frequencies.

Another disadvantage of the microphone is its sensitivity to sound

The first result of the microphone's sensitivity to vibration is that any vibration that is amplified becomes annoying sound. For example, you can hear this sound by rubbing the body of a hearing aid (such as clothing close to the hearing aid); you may hear this unpleasant noise when you vibrate the body of the hearing aid directly, or when sliding on a hard surface. The second result is that when the hearing aid receiver is operating, it produces vibrations that are the same as sound. The microphone picks up some vibrations, converts them into electrical signals, and then they are amplified by the hearing aid and passed through the receiver to produce greater vibrations. If the mechanical transmission of this vibration from the receiver to the microphone is strong enough, and/or the gain of the hearing aid is high enough, this feedback loop may cause audible vibrations, which are usually at low frequencies. Hearing aid designers avoid this feedback through careful installation and arrangement of microphones and receivers, but if any one of them changes the position, the hearing aid will be unstable due to internal feedback. If the microphone is installed at the entrance of a slender tube, the Helmtz resonance will shift downward in frequency. This will result in a larger peak in the gain-frequency response, and the frequency gain above the peak frequency will rise rapidly.

The last disadvantage of the microphone is wind noise
When the wind hits an obstacle, such as the head, pinna, or hearing aid, turbulence occurs. Turbulence consists of pressure fluctuations, and the microphone indiscriminately converts these turbulences into sound, so that low-mid-frequency noise can be heard. Keeping the microphone inlet away from the wind direction can reduce the amount of wind noise. A concealed and effective, but unpopular treatment method is to put some plastic foam at the microphone port; secondly, a better method is to put the microphone port deep into the ear canal, so deep ear canal CIC hearing aids have appeared. . Third, the less effective option is for the manufacturer to place a mesh screen on the open microphone port so that there is little turbulence into the microphone port.

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