You have a choice to make here. Return it fast as defective and try another. Accept it and try putting your finger over the mic or other muffling to see if the sound is too much for the mic.
Folks seem to learn the audio area faster when they get into recording such. I prefer an audio recorder and then fix it all up in post production.
Bob
I have a FujiFilm FinePix AX 300 digital camera, with HD video capability.
I have yet to get it to record video with clean ambient audio music. I am using a cd player for background music. It starts to play for about a minute, then sounds like the camera was flushed down a toilet. I turned off florescent lighting, I moved the music source farther away, I made sure my download USB cable is not hugging the PC speakers. It is the same almost every time, starts ok, then gets completely harsh to the ears. I started with fresh batteries, tried HD and SD, checked most of the settings. It is a new camera out of the box, first time out, it did this. Pictures seem fine, and video looks good. I don;t have my finger over the mic.

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