Thank you Akkana and Ted, my problem with the beeps has ended.  Your suggestions, observations and questions were on point and indispensable for helping me locate (and comprehend) some exact instructions for how to resolve the issue.

Here's how it went:

On 6/12/22 19:08, Ted Pomeroy wrote:
Tom & NMGLUGers, It may be a BIOS signal. ...Running 'top' in commandline while I do the logout shows the same Xorg and webcontent activity I am using and no other new action at the same time. I wonder if it is an Acer bios issue.
Indeed all indications appeared to point in the bios direction.
.... Have you searched the bios settings
Yes, more than once, but nothing useful accessible there.
...and checked the status of the bios battery?
Hmm.  Again, no access via bios, and I suspect not particularly relevant at the present time as I never seem to hear anything like "beep codes", only a single beep.  But that's an interesting question that might in the future be useful to have an answer for.  Is there a way to you know of to access status of the bios battery from a regular terminal command line?

On Sun, Jun 12, 2022 at 6:43 PM Akkana Peck <akkana@shallowsky.com> wrote:
Tom Ashcraft writes:
> But the most glaring and mystifying issue, i.e. the (loudest) beep upon
> unplugging and replugging the exernal power supply/battery charger remains. 
> Nothing makes it go away.

This seems to be an Acer (mis)feature. When I googled
    acer netbook loud beep plugging unplugging power
I got lots of hits. It appears that the (mis)feature is called
"Power Control Beep" and many Acers have an option in BIOS to
disable it, so look there first.
As above, been there done that.
If not, try a web search with your actual machine model (you didn't
tell us the model, you just said "Acer netbook") along with Linux
and "Power Control Beep", and you might find advice specific to
that model.
Bingo.  I thought the neofetch host line (AO722) that I provided in my original post was sufficiently clear and obvious, but I suppose I might better have been more direct or explicit and thorough.  The label on the bottom of the computer says Aspire one 722-BZ480 and MODEL NO:  P1VE6.  As it turns out 'Aspire one 722' was the most productive search string (or the most productive portion thereof) -- just as you suggest it might be.
...You might run alsamixer or ulsamixergui to see if alsa has a channel
like that, in which case you could set the volume on that channel
down to zero. If alsamixer or alsamixergui don't see such a channel...

Alsamixer *does* have a beep channel, just as you suggested it might in your *first* response to my *first* post.  I just couldn't quite figure out how to find it, didn't correctly comprehend the manner in which it remained obscure.  A case of "out of sight out of mind".

The rest of the story:

Pertinent results from Google search terms     
'linux beep acer aspire one 722-BZ480', the exact links:  
    
https://www.google.com/search?hl=en&q=linux+beep+acer+aspire+one+722-BZ480
    
https://ubuntuforums.org/showthread.php?t=1824927    
    
https://housegeekatheart.blogspot.com/2011/10/disable-ac-adaptor-beep-in-portables-in.html
    
Excerpted from the second link, the clearest and most    
effective description I needed to be able to deal with ALSA.    
It works exactly as described:    
    
This is the answer to the million dollar question: disable the AC adapter / power cord beep in Acer Aspire One AO722 netbook in Ubuntu 11.10.
...   
Then use the utility    
# alsamixer    

For portables there are no separate system speakers for the system beep, therefore the desktop methods won't work.  For some portables, there are two devices, one for the digital HDMI and one for the analog speaker and headphones.  You have to pick the correct one for the volume settings.

For the AO722, use F6 to pick the conexant sound card, rather than the first HDMI sound card.

Then use the arrow keys to get to the beep column.  Type m to toggle the muting status.

The heart attack beep will be off when the power cord is attached or removed.  But the beep is not altogether muted.  The beep volume seems to be coupled to the master volume or the alert volume.

Thanks again,

Tom