Siri/dictation not working

I'm using an iPhone 6 and it worked perfectly for several months until siri and dictation started picking up static when recording from the front microphone. The microphone itself is fine because google, voice memos, shazam and other apps that use it still work normally. I've tried resetting by holding the home and lock buttons and a few other ideas that people have suggested but nothing has made any difference. Filming from the front camera has the same effect and shouting cannot be heard over the buzz.

I'm open to any ideas that people have.

Thanks in advance for any help.