Sadly, in my opinion, R3 adds back the startup sound that I find annoying and unnecessary. I've sent feedback suggesting that Intuit make the sound a Startup Preference. I like having the register sounds, so turning them all of isn't a desirable solution.
Turns out that the Quicken Sounds folder has a bunch of opening sound files. I changed the name of the qopen.wav file so that it will no longer be found. But I decided that the qopen_2000.wav sound wasn't so bad, so I made a copy of that file and named the copy qopen.wav.
Bernie