Is there a way to disable the windows bell when the find in page feature of the browser returns no result ?
I think the only option to disable the "not found" sound in chrome is to change the "Default sound" in the Windows Sound Scheme (if we are talking about Windows OS) as it uses system sounds. See screenshot below.
The problem is that it will disable that sound system wide not only in chrome!
Disable Default Sound in Windows in the Sound Control Panel on the Sounds Tab: