iPhone Calls Sound Weird? Try Turning Off Phone Noise Cancelation in iOS
A feature called “Phone Noise Cancellation” is available on iPhone which aims to reduce background ambient noise when on a phone call, but for some users it can sound strange and make their phone calls sound weird, or worse. This may be due to the ambient audio stream created by the feature. Apple describes the option as follows, “Noise cancelation reduces ambient noise on phone calls when you are holding the receiver to your ear.” In other words, because the feature only works the iPhone is held up to your head, you won’t notice it all if you tend to make iPhone calls through Bluetooth in a car, headset, speakerphone, or earbuds.
If you think your iPhone calls sound off but you can’t quite pinpoint why, or you feel a little weird when holding the phone to your head while on a call, try turning off the ambient noise reduction feature and see if that helps.