Why does it crackle whenever i watch a video?

It started recently whenever i watch a video there is an annoying noise my inter net speed is Speedtest.net by Ookla - My Results. And my computer is Windows 7 64 bit Google chrome 39.0.2171.71 m. Plz help and if there is anything i need to add i will edit it.

Have you tried another browser?

Enable hardware auto-updating via Windows Update (Steps 3 and 6) , Check for Updates, install all Important and Optional Windows Updates to be sure you have latest drivers and patches to make hardware work correctly.

If these steps aren't enough, Try updating your Sound driver from the Dell Support Downloads webpage for your tag number.