电声设计培训教材之四音频电路设计传声器放大电路设计语音通讯传声器放大电路设计自动电平控制（ALC：Automatic Level Control）为什么需要ALC？在听阈与痛阈之间声压级的差异达140dB，理想情况下，转换成电信号幅度的差异也是140dB。而语音通讯电路的动态范围一般达不到140dB，如果不采用ALC，声压级高的声音转换后的电信号就会出现削波失真，而严重影响语音的清晰度。ALC的原理Noise gateA Noise Gate or gate is an electronic device or software logic that is used to control the volume of an audio signal. In its most simple form, a noise gate allows a signal to pass through only when it is above a set threshold: the gate is open. If the signal fa
