Just rode regional Air China flight, they were kind enough to announce at the start of the flight “Please notice, we consider airplanes to be a public space, and for security purposes we may record audio and video during the flight.”

Interestingly enough, that same announcement wasn’t made on the China -> USA leg of the flight. I don’t know about airplanes being a public space, but it’s definitely private property and companies can and do record on their property for all manner of reasons, marketing will be the primary driver I awesome.

What would audio analysis tell an airline about additional products / services they could be selling customers that are currently untapped?

I for one tend to complain about my seat, mainly mumbling to myself, but if I had a offer to move to any open seat for a $20 fee. I’d take it in heart beat.