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DesktopWeb FormText   eva : ghosts in the machineWed, 28 Jan 2009 15:05:47 GMT # 

have you ever been woken up by a synthesized voice? let me tell you ... Scary. /eva has woken me up in the middle of the night a couple times. each time involved her repeatedly saying 'you're welcome'. she does have a 'pleasant' grammar to respond to thank you, good night, and such. but the question is who (or what) was saying 'thank you'? so i started logging all the audio input. ends up it was white noise that was getting introduced on the line. that is actually why Eva has 'demon mode' functionality, because the first thing you have to do with white noise is play it backwards to listen for any demonic voices. the funny thing is static played in reverse sounds just like static ... boring. the workaround for that was to add a dummy grammar of 1 and 2 word commands that would be recognized, and then nothing would happen (i.e. Eva would not speak a result). but then i added the functionality for 3 quick beeps on rejected recognition. this lets the user know that Eva heard something, but it couldnt be recognized. this caused Eva to wake me up again, this time she was beeping at night. checking the logs, it was white noise again. so i changed out the cabling for better shielded cables. next night, more beeping ... but this time i noticed the time ... backup time. so somehow whenever a Windows Home Server backup kicks off, its introducing noise. i'm not sure if its from the wires physically running past the WHS, or if its just the act of backing up on Eva's host computer? anyway, the collected samples of static have all been very low volume (~100, while a spoken command is ~2000), so the current fix is to just ignore any low volume rejected recognition events. if that doesnt work, then i'll have to write a method to check for static itself.