That's not really telling us anything. The way you convert a time domain signal to a frequency domain signal, that is fourier analysis. There are other uses for it too, but that is the primary use.
FFT gain = 10*log(M/2)
where M is the number of points processed in the FFT. Doubling the number of points, lowers the apparent noise floor by 3 dB.
(I don't know if that's what the researchers actually did. I'm just explaining what the comment presumably meant.)