The trick of twisting the helmet straps - that makes sense. Will try it on today's ride.
For those who find ear buds uncomfortable - on the recommendation of several people on a musician's forum, I ordered a set of assorted sizes of memory foam fittings for earbuds. Much more comfortable, and the bass is much improved.
I wonder whether the triathlon organizers who prohibit earbuds would allow them if they were used solely for wind noise control, without an mp3 player attached.