From Anonymous on 2017/11/16 11:29:19 +0000
Hey, maybe the Echo devices can be used as sleep trackers with sonar. The speakers and microphone array are better than most smartphones and few devices easy to optimise 
Thanks for your app and have a nice day !
Copied from original feature request: http://urbandroid.uservoice.com/forums/264867-sleep-as-android/suggestions/32278705-amazon-echo-sonar