Buzzing on Acer Aspire laptop-

[Outdoor07]

I have an ACer Aspire 5750 Laptop running Windows 7 Home edition 64 bit which makes a loud buzzing sound when volume is above 19 which ceases when earplugs/ external speakers are plugged in. The problem ceased when I reloaded Windows 7 after replacing the HDD but then recurred when I restored a SYStem image. I am wondering if I can do anything to resolve this other than reload Windows as there is software I need to use on the System image.
Thanks for any suggestions

 

[Outdoor07]

The issue was resolved when I uninstalled the driver and then reinstalled the Realtech audio driver. I thought i had done this previously but it has worked this time...