[dustcoin]

    The mic/speaker assembly are in the middle of the window
    but the window has substantial size relative to the
    dimensions of the room and the distance the listener is
    from the device.

For what it's worth, the pictures in the article show a series of rings around the device that significantly increase its surface area, a component that is not present on the device in the video.

[msandford]

Yeah I'm not optimistic about those. They're clearly too small to be electromagnetic drivers (think magnets and coils) so best-case they're active piezo devices that are epoxied on (need to have a good bond) turning the whole window into a radiative speaker. Sadly those are limited to high frequency sound only (several kHz and up) so they wouldn't do much good for anything other than perhaps the bottle noise.

http://en.wikipedia.org/wiki/Loudspeaker#Piezoelectric_speak...