Apple has an audio lab that it's been using for years. It's in Cupertino and contains a number of interesting rooms, including "one of the largest anechoic chambers." Until I saw this report, I was unaware of such a facility.
http://www.loopinsight.com/2018/02/0...epod-audio-lab
I'd be curious to see the spinorama on Apple's HomePod to compare it to some products we know and love.