iPhone 7 Plus microphone issue

I am having issues with an iPhone 7 Plus. I'm not sure whether this is an audio IC problem or just the microphone. Dictation doesn't work and Siri can't hear me, but when I plug in headphones it does. Voice memos work and record properly. When I make a video with the rear camera it records the audio properly, but when I record with the selfie camera there is no audio for a few seconds and then it kicks in. Would this be caused by a faulty front camera and microphone flex cable? Thanks!