If encountered these problem on nokia e90, you may need to replace the Digimic module (digital microphone).
But before that you may first check and trace the microphones supply voltage and clock line paths.
The solution below shows the particular spots or components where to start or check these corresponding connections on Nokia E90 microphone's circuit
Nokia E90 Mic, mrophone or mouthpiece repair solution
Just follow the spots where to check and test the microphone's supply voltage and audio clock signal is is feeds from the power and audio IC (Avilma), the microphone's data signal is feed to the application processor(RAPIDO).
If all the line paths is all okay you may then proceed in replacing the digital microphone module.