Microphones are devices which detect sound signals and produce a voltage or a current which is proportional to the sound signal.
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When you talk into a microphone, the micro without power will produce an electrical signal.
A. 对
B. 错
Using a multimeter, you can measure the peak-peak amplitude of the electronical signal.
A. 对
B. 错
An operational amplifier circuit can amplify a sound signal.
A. 对
B. 错
不属于学生适应能力提高的方法是（）
A. 封闭自己
B. 积极与外界接触
C. 建立新的学习动机
D. 养成良好的生活习惯
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