I didn't talk about ultrasonic mobility aids in my answer, I suppose if you really found you liked a sonic guide or the like and really trained hard with it, you might learn to tell the shorter poles that usually have the push buttons, but in my experience they're not always on short poles, often they share a pole with some other lighting fixtures.
Real problem with the ultrasonic aids is they give you so much information that is of no use or worse, you spend a deal of timing trying to sort the wheat from the dross. tom
