How do I use the Toshiba Diagnostic Tool? Is this part of the Control Panel?
The Toshiba Diagnostic tool displays the basic information of your Toshiba notebook and diagnose its built-in devices.
Here you can find more details:
http://aps2.toshiba-tro.de/kb0/FAQ2503AW0000R01.htm
However, I’m afraid this utility will not help you a lot…
From my point of view there is an technical issue with the right built-in speaker.
I think only speaker replacement would help to sort out this problem.
By the way: is Smart Audio installed on your notebook?
Check the control panel… if its installed, check the settings and disable the “3d immersion”