Hi,

There's a neurological reason for this too, our brains are much better at detecting differences in pitch at higher frequencies, and are better at detecting differences in timing at lower frequencies.

This explains why lower-pitched instruments carry the rhythm in the music of cultures all over the world.

http://www.nature.com/news/rhythm-is-heard-best-in-the-bass-1.15481

Cheers
Kent
PG Music