The noise of an electret condenser microphone mostly comes from:電容式麥克風雜音大部份的原因來自於:
1. Impure current sourceIf the direct current mix with the alternating current signal, we will hear a stable level, low frequency and continual noise. We can lead the power to the microphone directly, or set a non-join circuit to filter the AC signal to improve the situation.
1. 電源不乾淨若是電源不乾淨(DC電中摻雜了AC信號),就會聽的到一個頻率穩定的雜音(通常是低頻),雜音音量的大小也差不多. 可改從電源處直接拉來給麥克風使用,或是加上退交聯線路,將AC信號濾掉.
2. Mechanism designThe faulty mechanism design might cause the wind sheer sound or resonant sound. Normally a deep curved sound hole is good to prevent the ESD, but it has some bad influence on the sound; for example, it is good for some frequency but some other frequencies might be declined. Therefore we may get unnatural sound with buzz or noise.
3. The noise from signalMicrophone is a component to receive sound, which can receive wider frequency range than human ears. Both high and low frequency signal will transform into noise as a form of harmonic waves after being received. An obvious example is that the noise happens when the cell phone and the blue tooth are set too closely. Therefore when we design the microphone circuit, we should keep it away from the antenna or other components which might radiate signal.
4. Outer noiseGenerally, the main noise is the sound of the wind. The users complain about the unclear sound because the higher join capacity receives the sound of the wind or breath. Modifying the join capacity (normally around 0.022~0.1 u) can solve this problem.On the other hand, if the outer sound (exclude the main sound) is too louder, it means the sensitivity of the microphone or the loading impedance is too high, what we can do is change to a low sensitive microphone or to decrease the loading impedance.
4. 外界雜音 一般此雜音都是風聲為主,使用者會抱怨聲音不清楚,很混濁,原因是麥克風交聯電容過大,把風聲或呼吸聲(氣音) 都收入而產生,只要把麥克風交聯電容改小(一般 0.022 ~ 0.1u )就可解決.如果是外界聲音(主要聲音以外的聲音)太大,表示麥克風感度過大,可改用低感度麥克風,或是因為麥克風的負載電阻太大 ,將負載電阻將低即可.