This TechCrunch article from last year goes into more details on the implementation, including a Q&A with the founders:<p><a href="http://techcrunch.com/2013/09/09/slicklogin-wants-to-kill-the-password-by-singing-a-silent-song-to-your-smartphone/" rel="nofollow">http://techcrunch.com/2013/09/09/slicklogin-wants-to-kill-th...</a><p>And here's a ShowHN thread (unfortunately light on interaction with the submitter):<p><a href="https://news.ycombinator.com/item?id=6359450" rel="nofollow">https://news.ycombinator.com/item?id=6359450</a>