traded my 2010 for a 2012 last Friday. the noisemaker is audible if you are 1. sitting inside while moving in ev with windows down (no ICE running) 2. outside of the car as it drives by with the same conditions as 1 3. driving with the same conditions as 1 but with a door open ... first time i really heard this was when i was backing out of my garage so i could look at the new LED's i put in ... door was cracked open a bit as i backed out i can't think of any other realistic ways you would hear the noisemaker, that being said, it sucks. no more stealth mode but factory led drl's!
I bought a 2011 Prius in part to avoid the noisemaker on the 2012's. I don't know why they can't turn it off on the dealership and why there is no off switch. Seems like the owner should have the choice of whether he wants the noisemaker on, as it was in Japan when this was first introduced. I don't think it is mandatory (yet) as it's not in all hybrids in other models. If it were mandatory now I could understand the dealership not turning the noisemaker off, for liability reasons. From reading the responses it seems it is not that loud but it does annoy some owners.
My 9 and 11 year old sons think the noise is cool. It kind of sounds like a space ship noise if you watch Sci Fi. We have a Prius V.
The first time I noticed it, I was going through the drive-up window at Taco Bell. It was a warm day & their window was open, so the kid at the drive-thru heard me pull up & was giving me a puzzled look as the "spaceship" sound spooled down. He never said anything, but the look on his face was priceless! Honestly, I thought the noise was legitimate at first and was suprised to learn that it was artificial. Not sure that I like it or not, but it doesn't really bother me. It would kinda be neat to have no sound at times. However, I think it does mask the sound transition to the ICE very well. If I didn't have it, I'm sure it would be much more noticeable when the engine kicked on.