Nearly started making these sounds before I realised I'm on a busy train and caught myself. Oops. If it helps at all, in my experience of learning to do alveol

Nearly started making these sounds before I realised I'm on a busy train and caught myself. Oops. If it helps at all, in my experience of learning to do alveolar trills, the key was finding the precise amount of resistance to apply with my tongue. That is, the muscles hold still and the flow of air is what moves it. I think that means that the base position for the tongue is forming a light seal against the alveolar ridge and upper gums. If you get the pressure right, when you vocalise, the flow of air will briefly push your tongue out of the way then allow it to snap back, and if you get the pressure exactly right, you'll get a pleasing trill sound.