On MacOS X, the built-in PING application has audible alerts. These alerts have quickly become my favorite options. I like to multitask, so I don't always keep my terminal window in front while doing continuous pings. I've gotten to the point that I almost always use one of these two options.
-a beeps when the remote side responds. Great for rebooting something to know when it is back online.
-A beeps when the remote side doesn't respond. Great for testing network consistency. I also like to use this one when applying updates or patches to a remote device so I know when it the reboot actually starts.
I did a quick check on other platforms, Windows 7 has no audible flags, Centos 6.5 only supports the -a option, -A means something else.