When we got the request to build an app to measure the RT60 value with an iPhone, my first thought was: “RT60, you say?” Right. I had no idea what it was, let alone how to measure it. I was told it was measuring a “machinegun”-sound, followed by some simple Excel-kinda-calculation to get the RT60 result.
Well, it turned out to be a little different. But we dug in deep and shot on sight. This is the story of a battle against Fourier Transformations, ANSI S1.11-2004 and audio ring buffering.