Pitch recorder. Just doing some lip trill exercises. I think the highest I ever got was an A10 and the lowest was somewhere in the B2 range. It’s neat to see. I love this thing. Fascinating to track notes and pitch. This is when technology is a positive thing. 👍🏽
Of course one of the originators of the whistle register besides opera singers the unfortunately gone way too soon Mini Ripperton.
And of course the masters of it