Electronic – Smartphone microphone sensitivity

Your circuit might almost work if you replace the microphone with a old carbon powder type. This is what old telephones had in the mouthpiece. That type of microphone looks like a variable resistor to the circuit, not the tiny voltage source your microphone probably is. With a variable resistor, you can just put it in series with the speaker and a battery and probably hear sounds picked up by the microphone in the speaker. If you can find a really old telephone with mechanical ringer, it might have a carbon mic in it.

Otherwise, microphones you get today produce a tiny varying voltage. This must be amplified to drive a speaker. Note that some types of microphones, called electrets, additionally need a few volts applied to it with a few kΩ imedance to produce that small varying voltage. Electrets often come in small cartidges like what you show, so you may have such a mic.

Usually electret/condenser microphones require power to operate. These microphones are also called as capacitor microphones. There is a capacitor whose one plate will move as per the sound waves. This will cause a change in the capacitance which is equivalent to the sound waves.

In order for these microphones to work, power is required. Capacitors has rtto be charged to see the capacitance varying. These microphones are powered from the same audio line of the amplifier. If there is no power reaching the microphone, then it can't operate. Hence it draws small amount of current.

It is normal that these microphone consumes power. For any electric circuit to work, current is required. Each device you connect to your phone will consume power. Since the current consumed is 0.17mA, you won't notice a big difference in the battery life.