I think most DU Meter users never used the “Audible network traffic monitoring” feature. And indeed, constant “beeping” is annoying if you have it always enabled. However, if you are waiting for a long download to finish, you can do this:
Go drink some coffee, stretch your legs, talk with your family or collegues. You’ll hear the beeping in the background, and when it stops, you’ll know the download is finished or stalled for some reason. It is a bandwidth monitor without a monitor. I’m sure you can think of other clever uses for this feature, please comment if you do!