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.
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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...