No microphone pickup when I make calls, what part should I replace?

Hi,

I have just replaced the screen on an iPhone 6. At first you could not hear anything on a phone call, nor could the other person haer you, however on loudspeaker you could do both still. I opened the phone again and cleaned connections etc, now you can hear what the other person is saying, but they can't hear you. Loudspeaker again works fine for both.

This is my first time fixing a 6 series so undoubtedly I have accidentally damaged something in changing the screen. I just would like to know which component or assembly is in charge of picking up voice on standard phone calls, is this something within the earpeice speaker, or is there a seperate microphone on that ribbon cable with the front camera etc which is most likely damaged etc? Just basically want to know what component to order to fix it, I'm sure it's just a smile accident on my behalf and I'm normally more than capable of replacing components on phones.

Thanks!