Great Feedback Tool
I have used this app and it is great for one reason—the size of the visual feedback. When I work with singers who are supposedly “tone deaf “ an abstract line moving up and down is often not helpful to provide immediate feedback. Setting the response to letters with octave numbers does the trick! The visual is large enough that their are enough “cognitive” resources to adjust pitch up or down and using the changes in the visual responses (e.g. A3 to Aflat 3) to learn pitch manipulation.