Speakers cutting in and out. new batteries?

I think i might need new batteries. So when my speakers are all the way up they seem to be surging a bit. more like cutting in and out. No one else notices it but me and my buddy. My batteries are 3 years old.. Deep cycle basic batteries powering 3 amps..... should i just pull those and put in two blue blue tops? or add the two blue tops? Or is this even my problem?