The problem was that on an Apple Macbook Pro, even though the Mac should remember the state of its output audio volume when last shut down, there's no way to verify what that was, after it's off, it's too late to push mute when off, and also, when you do the sometimes-helpful PRAM "zap," during start-up (by holding down Command + P + Option + R), the last saved muted setting is forgotten (!) and the obnoxious "Bong!" chime sounds, as if you either A: don't know what you're doing, or B) think someone will be impressed that you don't know how to start up your Mac discretely... Free coffee-house acoustic harassment. (; That "Bong?" It's a synthetic sample of the last note in the Beatles' "A Day in the Life," which was recorded into the lock-out groove on vinyl, and should be an eternally playing sound, actually. So, the single "Bong!" that is immediately dampened is, itself, a "fail," but hearing it is no guarantee that things are ok with the Mac (even though that's the official Cupertino shop position on why it can't fully be muted against all occurrence), and it would be obvious if there was something wrong after it finished trying to start up....
A pentalobe screwdriver is necessary to be able to open the uni-brow (I mean, uni-body) laptop in order to unplug the internal speakers. They sound ok for their diminutive size, but, I prefer to use the external audio output port and connect the Mac's sound to a stereo, with its own ergonomic and always-identifiable settings, plus much better stereo reproduction (through better speaker separation and diaphragm size... (;). By the way, Apple once hired a guy to examine the original single speaker and, without increasing cost, improve its sound. He told them to put it in the front of the computer aiming at the listener's general direction, rather than having it aimed away, on the back, next to the case fan! Solved.
Repair went great. Although the pentalobe screwdriver, as well as my mini-Drivers of other formats wouldn't open the screws inside without starting to strip the blade sockets, I was able to lift the speaker connector plugs off their respective pads and now the Mac doesn't "talk back" anymore, unless I tell it to!
Computers are great, but we have too many obnoxious robotic sounds in our modern, appliance-heavy society. Car alarms, big trucks in reverse (beep- beep-beep), or fake Beatle bongs from Apple laptops. Schopenhauer points out that sounds should be startling and vexing to people with brains, since the auditory signals go right next to the medulla oblongata in our brainpan, which is a lethal zone, if actually disturbed. We don't usually jump, with a start, in the presence of a flash of light, but a sudden sound can make us jump... and should!
I put a kill-switch on my Hitachi TV, also, because one can't know what the digital volume control setting is until the tv is turned on, and then it's too late to mute it, if wanted. So many dynamos! I like to fix things: