[thehappypm]

My washing machine also makes a stupid chime melody thing. A microphone that listens for it would also be a simple way to do it.

[lillecarl]

I would go for the "monitor a number" before "sound recognition", unless you're talking about just using an amplifier to bring the chime into the entire house.

[thfuran]

I'd dump cut the mic and wire it to some input before actually trying to check for the sound. But it's probably inconvenient to get to and monitoring overall power draw would be easy.

[imglorp]

Or a current sensing transformer around its power cord.