Could you take a look at this audio file for me? It's got some horrible MP3 artefacts or something.
author: Rich Wareham (rjw57)
The puzzle is what appears to be a broken audio file. The title is a reference to Fourier's Law and "Joseph" is Joseph Fourier himself.
Aside from investigating thermal conduction, Fourier is also famous for the Fourier Transform which is used to generate Spectrograms.
Loading the file into Audacity and using these settings for the spectrogram view:
gives the following:
The QR code can be scanned directly from the spectrogram to give the answer "thinker gear security". Other spectrogram visualisers can be used, of course, but Audacity's allows for lots of tweaking. Some teams transcribed the QR code directly or touched up the image in an image editor which are also valid solutions.