I am Makarand P from the Dell Social Media and Communities team.
With regards to your issue, may i ask if you face the same problem while playing cds or dvds on the computer. Have you tried playing videos on an another browser, if yes, do you face the same problem. Do you hear sounds while computer starts up. If yes, i would suggest you to uninstall the sound drivers and reinstall it back again. If no, i would suggest you to install a freeware called VLC player. It comes with extra sound drivers and add ons and would greatly improve sound quality on the computer.
Kindly revert for further clarifications,
Thanks and regards,
Dell Social Media and Communities Responder.