Why do I hear static sounds from inside the phone?

I have a huawei p9 lite mini and 2 days ago I noticed some weird sounds coming from the inside of the phone, when i listen close i can hear a static like sound coming from the middle of the phone to the top in the ear speaker , i firstly noticed that when i was in a phone call and i thought it was some sort of signal or something but it keeps going and i don't really know what to do, or what it is exacly. Have to mention that phone is now charging very slowly and sometimes the temperature increase.