I have a Toshiba L555 running Windows 7 and have started having the same problem. I have tried most everything suggested on the internet with no success. It appears this problem is purely a Windows 7 situation. I have Windows XP and Windows 8 on two other laptops and I have no problem with the intermittent buzz sound. I've come to the conclusion that nobody out there knows the solution. I keep searching, but I have yet to find the answer that actually works!
I've had my Asus U56E since last summer, and I've been experiencing an intermittent buzzing noise any time I play any sound on the laptop. This happens if I'm watching DVDs, using iTunes, or any online video, music, radio etc. It happens about every minute or so and the buzzing lasts 1-2 seconds. I contacted Asus when I had this problem about a month after purchasing, and they told me to do a system restore which I thought was a quick fix. However I did it and it did fix the problem temporarily, but it just returned about a week ago.
I tried re-installing the audio drive and that didn't work either. I'd rather not have to do another system restore and lose everything yet again, so I'd like to try and isolate and fix the problem if possible. Everything else on the laptop works fine.
Here is all my info, please let me know if you need more information:
Intel Core i5-2450M - CPU @ 2.50 GHz - 64bit OS - 6GB Ram - Intel HD Graphics 3000 - Realtek HD Audio