What is the name for the device fitted to a bathtub faucet, that changes the flow of water to or from the shower head?
Tub spout diverter.
yep. lemme guess, yours is screeching.
Like Harpo Marx.
:dubious:
I’ll bet it’s been called a ‘thingamajig’ or some similar kind of word far more often than by it’s proper name.
That means I’ve never heard it make a sound.
I hoped so. 
Anyone else mildly relieved this isn’t another bathroom bill discussion?
Yep.
I’ve never heard of Bathroom Bill, but Jay Leno pointed out a typo in a costume ad: mentioning “Bathman” (should have been Batman, of course). Leno commented, “I’ll bet the Bathman stuff is *really * discounted.” 
Maybe, but my 4 year old has a batman bath wrap with cowl that is freakin’ awesome.
I’m offended with the word diverter … it’s just a normal tub spout verter
ETA: Huh … this thing violates the ADA regulations … seems like everything is outlawed these days … photo
But it’s environmentally compliant.
Do you suppose its the Dental or the Diabetic Association?