osx comes with a command "say" which is a text to speech tool. I'd do things like make && say "build complete" || say "compile failed" with different voices I thought were funny. generally worked great.

One day, I stepped away and had a particularly intimidating voice say "your build has failed" and apparently knocked out my headphones. I came back just in time to hear that, and see a couple coworkers jump at the sound.

After that, I was much more consistent at disabling sound when I stepped away. I got a little teasing about that day, but generally it worked great.