My ear sometimes makes crackling/fluttering sounds when I use speakers?

I feel and hear a fluttering/crackling in my ear when I am using speakers (usually a Nintendo DS when this happens). Whether or not I am using headphones seems to be irrelevant. This only occurs in my right ear, and only for about 30 minutes or so. The problem seems to have no patterns or tendencies in its occurrences other than when I am using speakers. This has been a problem for about 2 years. Any ideas?