Research behind the Facebook ping From an answer on Quora:

I designed most of the audio currently in the product today. There are a few major components that make up the audio identity. First, is the base chord which is an Fmaj7 chord. For you music nerds out there, yes, these notes actually spell out “FACE”.

Some more background. Fascinating that people so involved take the time to share details we could not otherwise verify.

(via @sanatrath)