Microphone

Hi

My microphone on MacBook Air 2013 seems not to be working. Test using input through system prefs seems to not register sound even when volume turned up but Siri and Dictation using Air's microphones (assuming they use the same mic) work fine. Trying to record audio or video with Quicktime does not work. Have done a reset PRAM - did not work.

Updated to Catalina - same issue.

Any suggestions

Thanks