To beep or not to beep that is the question

An ETryko Electric Tricycle is quiet. In fact it is almost silent except for the tires. At slow speeds it will be nearly impossible to hear. For this reason, we supply each ETryko with a speaker to make a beeping noise.

It will automatically come on whenever the tricycle is in reverse. When a driver is in a crowded area, the driver can turn it on manually. Of course, they will still be able to use their horn.

One alternative is to play music.

What sound would you want?