Have to say I broadly agree with this. While I'll go beyond Tunborough's assessment and grant you have pitches above three octaves, there's no consistent upward progression, nothing I'm hearing close to four, and nothing reliable anywhere close...Tunborough wrote:The other sets of notes bounce all over the place and I'm not sure that any of them goes much above D7.
For something approaching reliable high harmonics, see my Holifield Low D Whistle video review (starting at 1:18), where I managed to get three octaves and a third of consistent upward progression despite still taking two goes to hit some of the notes. So maybe see if you can get that far on your high D without a single descending interval?