My Tennadyne T12 'sings' in the wind, and it can be annoying. I think it's
due to the ends of the elements being open, and they act like little organ
pipes, creating a rather mournful sound.

I would not care about this, but unfortunately my neighbors can hear it,
they say it does not bother them, but I think it would be a good idea if I
could suppress this sound.

The ends of the elements are likely open so that they will drain any water
than might get in, but I don't think it would be wise to cap them.

All that would seem to be needed was some material which could be placed in
the ends, which would allow water to pass through, but be sufficient to
suppress the organ pipe effect.

Any solution to this?

Ron, N5IN