Why I can not hear when I answwer my without using my speaker.

Hi,

Just to eliminate the remote possibility that it is software that is the cause of the problem, try starting the phone in safe mode and check if it is still faint when on a call.

If it is then the earpiece speaker may be loose or faulty and it needs to be checked or replaced.

Here’s a link to the ifixit 三星 盖乐世 Note 8 拆解 guide which should help you to open the phone so that the earpiece speaker’s connection can be inspected or the speaker be replaced if necessary.

Here’s a link to a supplier of the part.

It is only shown to give an idea of the cost of the part and what it looks like. There is also a video that shows how to remove the earpiece speaker. Start watching at 5:56 minutes into the video.

There are other suppliers online that may suit you better. Just search for Samsung Galaxy Note 8 earpiece speaker to get results