How can you describe in an e-mail how tremelo is supposed to sound?
OK, how about this. Ever lightly pat your hand over a baby's mouth while it's crying or making some noise so you get a wah-wah-wah kind of effect? Now adust the speed of the "patting".
(Shorter time intervals between wah-wah-wah's or longer time intervals between wah-wah-wah's.)
How's that?