iPhone 6 audio is distorted when listening through earphones? Any Solution?

So when listening to any sort of audio or sound via my earphones, whether that's a YouTube video, the keyboard sound or listening to music, it occasionally suddenly becomes distorted, almost like loud white noise!

a short term fix I've found is to force shutdown the device however I don't want to be doing this all the time.

Plus its not a very noce sound to wake up to when I've left my earphones in hen ice slept and I wake up to this horrible noise

Also when one the phone to someone, people on the other end has said its like they can hear minions talking where on my side I can't hear much and when sound does appear it's very slowed down and deep (quite weird!)

Any advice or solution?

Thanks!