I'm making a single chip microcomputer noise meter, and the microphone (electret microphone) is used as input. How to design the following circuit?

It should be said that as an instrument, you should use the instrument operational amplifier, because its linearity is better. Traditional instruments may have higher requirements for such equipment. You use a single chip microcomputer, so it can be solved by software to a great extent. The voltage required by instrument operational amplifiers is generally relatively high, such as OP07, which is not suitable for single 5V, and it is also very expensive. From the cost point of view, LM358 is more suitable. In addition, 358 can work at the lowest voltage of 2V, or plus or minus 1V, 5V can be used as the midpoint of the virtual ground as plus or minus 2.5V, or it can be directly used as a single 5V to supply power to 358, so it is the first choice.

Then there is the problem of linearity, because the electret microphone itself and the operational amplifier itself have different responses to different frequencies and sound pressures, and the connection of your circuit itself will also affect the frequency response and intensity change. Most importantly, don't over-amplify to prevent distortion at the top of large signals. If possible, set more gain gears and cooperate with the software to realize the automatic range function.

In software processing, a sound source with reference intensity can be used for correction. Finally, the correction table is stored in the program, and the overall linearity problem caused by components and circuits can be corrected by software. In this way, the linear problems brought by each part are solved.

Just mentioned the problem of frequency response, so don't forget to make different corrections for signals with different frequencies when correcting. It may be a bit difficult to use ADC0809 because its sampling rate is average. If it is a little difficult to do frequency analysis, it is still possible within a certain range, and FFT algorithm can be used for analysis. Due to the complexity of the signal, the timing method is easy to get the accurate center frequency.

So in general, the circuit is not a problem, and the software part is more difficult.