Like loopie said, we need some more info. Some polyphenols, specifically tannins, will drop out over time from gravity. Others stay stuck in suspension pretty much forever. If you're getting astringency from grain husks, hope, or oak, they will diminish over time. Not much help for a hoppy beer, but some styles benefit from aging and would show some tannin reduction over 6 months to a year. Not much you can do to mask these flavors, though.