Other people have complained about the number of participants, but that isn't the issue (it was run as a crossover study, so 13 participants should probably be

Other people have complained about the number of participants, but that isn't the issue (it was run as a crossover study, so 13 participants should probably be fine). The issue is that despite purporting to test fancy pink noise synchronized with brain activity, the control treatment was no noise rather than unsynchronized pink noise. That means that it's impossible to tell whether the synchronized noise was more effective than normal pink noise would have been (or even possibly just earplugs, although it looks like the earphones they used do a decent job of blocking noise: https://www.amazon.com/dp/B0046H8ZHS https://www.amazon.com/dp/B0046H8ZHS ).