Great question, I’ve wondered the same thing and have had the same experience with whistling.

I’m not sure and I could be wrong (anyone correct me if I’m mistaken), but my take on it is that there are direct similarities in how we engage/tighten the aperture corners, arch the tongue and perhaps control the air (and not over-blow) when doing whistling and playing trumpet.

When I whistle, I tighten the aperture by tightening my lips around the aperture/air column while arching my tongue and it feels like the fleshy middle of my top lip is the key to the highest pitches I can reach.

One thing I have done since starting WindWorks is to focus on clamping down (top to bottom, rather than tightening from the sides/corners) my lips as I whistle and I’ve noticed that it stops the sound as it tightens the top/middle of the lip which is the vibrating surface. That helped me solidify my understanding of what Greg was describing, FWIW.

I do feel some similarities to how things feel when I play trumpet; it’s obviously not the same but I do think there are some similarities.

I’ve looked online but haven’t found any information.