The speakers are not working properly

I have been using a Dell XPS(L502x) laptop since 4 years. Till recently my speakers have been working well. But they started giving a Grrr..... noice whenever I listen to music or see movies from past few weeks. I usually use both speakers and headphones to listen. What is the reason for this? Is this because I use headphones more than the speakers??

Awaiting a response,

Thank you.