If nothing else this one is so odd that it’s worth the entertainment value for your choir.
As your local reflexologist will tell you there are lots of important spots in the outer ear.
Have your choir members stand still and really listen to any ambient sound. Then, just for fun ask them to twist their heads around first to the right, then to the left as far as they can – and notice how far that is.
Next, ask them to massage, quite vigorously, their outer ears – and finish up with slight pulling on the ear lobe.
Two interesting effects can be noticed after this exercise. Their hearing will be a little more clear and crisp – and they’ll be able to turn their heads farther to the left and to the right.
No idea why this happens – but a more relaxed neck, and hearing that works better are both desirable for any singer.