Microphone Problem

hi guys,
i’m currently works on webAR project that using speech input for controller(or trigger action) using unity3D. After i build and open the link on my browser (chrome), i got error said:

("An error occured running the unity content on this page. See your browser javascript console for more info. The error was: uncaught nonsupportederror: Failed to execute ‘createBuffer’ on ‘BaseAudioContext’:the number of channels provides (0) iis outside the range[1,32])

can someone explain what’s wrong here?