The hole next to the headset on the Huawei c8650 mobile phone is a noise reduction microphone. Noise reduction microphones use directional processing of sound signals to improve the signal-to-noise ratio, so that users can hear the opposite person clearly when there is background noise. The basic principle is to assemble two microphones in the same hearing aid according to strict acoustic principles, so that the sound signals from different angles can be amplified differently, so as to enhance the useful signals,Relatively reduce background noise.
The hole on the top of Huawei 9xpro is an auxiliary microphone!Also called noise reducing microphone! Dual microphone noise reduction technology is the most common noise reduction technology in large-scale application. One microphone is used by ordinary users to collect voice while talking, while the other one is equipped on the top of the body, which has the background noise collection function to facilitate the collection of ambient noise. The mobile phone is equipped with two condenser microphones A and B with the same performance, wherein, A is the main microphone for picking up the voice of the call, and microphone B is the background sound pickup microphone, which is usually installed on the back of the mobile phone microphone and away from microphone A, and the two microphones are internally isolated by the motherboard.During normal voice communication, the mouth is close to microphone A, which produces a large audio signal Va. At the same time, microphone B will get some voice signals Vb more or less, but it is much smaller than A. These two signals are input into the microphone processor, whose input end is a differential amplifier, that is, subtract the two signals and then amplify them, so the signal obtained is Vm=Va Vb.If there is background noise in the use environment, because the sound source is far away from the mobile phone, the intensity of sound waves when reaching the two microphones of the mobile phone is almost the same, that is, Va ≈ Vb. Therefore, although the background noise is picked up by both microphones, Vm=Va Vb ≈ 0 From the above analysis, it can be seen that this design can effectively resist the environmental noise interference around the mobile phone,Greatly improve the clarity of normal calls. However, there are two sides. Although the dual Mic design can effectively resist background noise, the cost is high. In addition, improper design may affect the normal pickup quality, such as AIf the isolation of microphone B is not good or the microphone is too close or the parameters of the two microphones are not completely consistent, it may cause normal calls to also cancel part of the pickup, resulting in low call volume. It is particularly important to remind that mobile phones with dual MICs must be correctly aimed at the microphone to get a strong signal. If they deviate from microphone A at will, or use hands-free mode,The output of the microphone may be greatly reduced. Therefore, when this mobile phone uses the hands-free mode to talk, the microphone B should be turned off. If you feel that the volume of the call is too small, you can also turn off the microphone B manually. At this time, the dual MIC noise reduction effect will disappear.In addition, because human voice is within a certain frequency range, sound waves in different audio ranges may reach A, A and A in certain wavelength bands due to the interference principleThe phase of microphone B is opposite, and the superposition will affect the output of this frequency band, that is, the frequency response is not straight, and the other party may feel a bit stuffy. I'm afraid this is also a disadvantage of dual MIC.
