Switching off all tones including Start up tone

I would like my Edge Explore to run silently as my old Edge Touring did.  I have switched off tones on the system menu and all tones are off EXCEPT the startup tone.  This is annoying as it drives my poor dog loopy.  She seems really scared of that tone and is often to be found cowering under the bed upstairs.

Is there any way of disabling the start up tone?