@explorermatt good to see you on the forum again bud. It’s been a minute! Those are the vowel shapes I used when I first learned how to bend, and that’s how I used to teach it as well, as in this vid from 11 years ago:
About 5 years ago when I made the Blues for Beginners vid I asked a pro harmonica player to critique it and I had said “if you don’t know how to bend, try say oy” (oh and ee) and he was like “What?!? That’s backwards, if anything, say Waoo”.
I was like What? This guy doesn’t know what he’s talking about! But then I tried it and to my utter shock I got a bend. This turned my world upside down. I was beside myself for several days.
How could opposite mouth movements both produce bends!?!?!
Then I consulted my Harmonica for Dummies book by Winslow Yerxa and he talked about the Kk spot. I think the lifting of the BACK of the tongue (which makes the front of it go down) is key, and I think both “ooo” and “aah” can create a mouth movement that puts the tongue in that position.
At the end of the day, according to Richard Sleigh, only one thing creates a bend, and that is tuning your mouth to the resonant frequency of the note you are bending to. I think this is why whistling from high to low, or doing “the airplane dive” as I describe in Bending for Beginners can be so helpful. SLOWLY moving the tongue back into that position at some point you’ll hit that frequency and get a little bend.
@explorermatt I’ve now gotten away from “eee” as the default way to come out of a bend as it creates very BRIGHT tone. I mean that can be cool sometimes. But I went through a period of “breaking the habit” because I wanted to also be able to release a bend into a warmer vowel shape, if that makes sense.
@angela_67 I’m so gad you are feeling encouraged and inspired to keep on trying. THAT’S THE KEY. There’s only one path to learning any new technique:
Try. And try again.
It’s so exciting the FIRST time you get a new technique, and then so frustrating when you can’t replicate it at will! I’ve been more recently experiencing this all over again with learning over-blows so I’m with you 100%.
Keep on trucking! 
@Slim this is so good, I think it bears repeating:
Yes and amen.