Take action at certain volume level

Lemme describe my problem before I get into my question.
I have a television in a public area and am having issues with people turning the volume up too loud. My planned underhanded solution to this issue is to wire some sort of sound sensor to an arduino and send the "volume down" IR signal once the volume has reached a configurable thresh hold. I believe I can handle the IR portion but without some way to trigger it automatically I am essentially re-creating a remote control. This is why I am think about the sound based volume threshold approach. I would like to power all of this via an arduino wall wart adapter (I already have this).

First, is this even possible?

Second, what kind of audio input hardware am I looking for? Some googling led me to "electret" microphones and many posts discussing how they don't work well.

I'm just kinda brainstorming ideas here. If anyone has other ways to solve my problem I'm open to them.

Thanks!

Mic is obvious solution, to measure a sound volume.

A lot of people just can't get right how to process AC waveform, which is an mic output.

But how will you know if what the mic is picking up is from the too-loud-tv or just people in the room getting too enthusiastic about what they're watching.

@jumbo: I'd consider that valid cause to turn it down as well :P. I imagine if their TV turns down every time they shout they'll get the idea.

@Magician: Can you elaborate a little more? Would it be a simple matter of higher/lower input values coming from the mic corresponding to higher volume? Reading the comments on that component leads me to believe it requires more complicated processing to get actual sound pressure.

Thanks for the help guys!

@jumbo

That’s Jimbo 8)

Would it be a simple matter of higher/lower input values coming from the mic corresponding to higher volume?

This is a specific of AC, lower value doesn't mean lower voltage level - in reality it's higher! Power is proportional to V^2, so it's doesn't matter if voltage positive or negative. To measure AC correctly, you need to rectify AC to DC, than low pass. In software , or hardware. The simple solution for electronics noob would be using LM3914 / 15 / 16 , where you can easy get required audio level from IC 10 outputs , just wiring up 1 or even all of them to arduino digital inputs.