u/ThatDruidOverThere

I just picked up learning the whistle and I don't know if it's a Low D Whistle thing, but when I don't blow hard enough with the first hole (left index finger) open, I get a lower note that isn't a D. It sounds like a Bb but when I look for answers I find nothing, except stuff about half holing which I don't think I am doing. Am I missing something ?

I really love this track and have never been able to find this exact remix, anybody has an idea ?