A coworker and I once did a similar thing (Just a beep, no vocoder) to isolate a faulty switch. This switch had been causing horrible problems (data corruption style) for weeks and we just couldn't find it.

It's the only time I've ever seen my friend violent or aggressive. Upon find the switch he calmly unplugged everything, and then threw the switch at a concrete wall. I understood the sentiment.

Some versions of ping have -a ("audible") option to ring the terminal bell on each response.

I had a friend do the same thing when we were trying to get point-to-point wireless between our houses. He was wandering over my roof with his laptop held in the air, with it chirping 'yes yes yes yes' as it found the better areas of connectivity (his commandline used 'yes', but can't recall it).

My first thought is that if you had to do that these days, you'd just run a terminal app on your phone over WiFi or something of the sort. My second thought is that the vocoder solution is basically setting up a one-way human-compatible wireless network over sonar.