The internal speaker (top speaker) allows you to hear the person you are talking to during a call. It needs to be replaced on the iPhone 7 Plus / 8 Plus if it crackles or no longer emits any sound.
5This internal speaker at the top generates the sound you hear when talking to someone on the phone. Here are some signs that indicate it needs to be replaced:
Replacement is very simple and takes about 15 minutes. No repair knowledge is necessary.