Speakers goes out when volume goes pass 40

[ilivmylife4mysons]

I have an 08 Es 350 lexus and my volume won't go pass 40 if I do i can't hear anything but as soon as I turn the volume back to 39 I can hear the radio again. Any suggestions 

[RX400h]

Such a situation happens because one or more speaker terminals are surely grounded to the metallic door. Has any work been done to the dash or a door?