When you go to a web site and you hear this adds can you see them?
If you can't minimize that page and see if you have another page open with that sound add playing.
Sometimes when you open a web page you actually open 2 or more pages. They run on top of each other.
Their is always a chance of a virus causing this also. I would run a complete updated scan with my anti virus program.
I use MSE and MAM. Microsoft Security Essentials - Free Antivirus for Windows
Computer type PC/Desktop System Manufacturer/Model Number Home made Desktop OS Windows 7 Home Premium 64 bit. SP-1 CPU Intel i7-960-3.2 @ 4.25 Motherboard ASUS P6X58D-E Memory KINGSTON KHX2000C9, Hyper X,12 GIGS Graphics Card MSI/Nvidia/460GTX-Cyclone 1GD5/OC Monitor(s) Displays DYNEX 40 IN. Screen Resolution 1920-1080 or 1280-720 HDMI
Keyboard M/S 3000 v 2.0 wireless Mouse M/S 5000 wireless PSU Corsair AX-850 Plus Gold Case Corsair 600T (Black) + side panel with 2 140 mm Noctua fans Cooling Corsair H50/2 Noctua NF-P12 (120 mm) Push/Pull- Hard Drives INTEL SSD 120GB-SER 510
Seagate 1TB SATA 600 7200 rpm Hard Drive Internet Speed 3.0 mb Antivirus Microsoft Security Eesentials Browser I.E. 10 default/Firefox Other Info LG BluRay-Read/Write
Sound system
KLipsch-THX
Asus Router RTN-12
2 Noctua 140 added on top of 600t case
Malwarebytes Anti Malware Professional
Windows 7 Firewall