I think the extra sounds are standard with the new system.
It was an option on the old that I bought thinking it would help if I ever sold them.
I was told by BB that the sound is the biggest battery drain of all the functions. Battery technology keeps improving so maybe it's not an issue anymore.
I have 4 BB's and didn't even put the speaker on the last one. I hardly ever used the sound. It's nice to check to see if you remembered to turn it on, or to see which unit is where.
It was also good as a battery checker as the sound gets cut off if the battery is low. If a unit didn't shoot from the line and you hit the sound and it worked at least you knew it wasn't the battery. I don't know if it's the same with the new units, but sometimes the first barrel would fire then not the second. By the time you walked out to check, the battery had regained enough to work again then would not work. This would be rare when the battery was really low. Sometimes you forget to turn them off... If you hit the sound you'd know right away.
I guess some use the sound as an attention getter for the dog which would be good if the marks were widely separated. In a tighter setup it's hard to tell where the sound is coming from.
It even has a "hey hey" sound but my dogs never got the idea using it for help.