Hello Reijer,

Yes, good question.

I suspect that someone will be able to point out a specific reference for this “Check In”, but until then, when I “Check In” at the end of the exercise, I check if it feels like I have played the exercise with the feeling of humming/singing (with the Body’s Concert Hall remaining open and without any unnecessary musculature or manipulation) or if I can feel any unnecessary musculature or manipulation.

Regards,
Marc