The Fourier transform unwinds periodic signals into flat DC

Evidence

There are also mathematically based procedures for the optimum placement of absorbing materials to encourage diffusion; for more details on this, see Angus (1995). What is required is an amplitude weighting, that is, a pattern of absorbers, which gives a flat Fourier transform. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2102 (#expands, via linked claim)

Categorization

• XREF: connects to: Complex real-world sounds can be analyzed via Fourier analysis — David Howard, Jamie Angus, coustics and Psychoacoustics, 436; The Fourier transform pair converts signals between time and frequency domains — David Howard, Jamie Angus, coustics and Psychoacoustics, 440; m-sequences offer flat Fourier properties suited to diffusion design (+4 more)

Broader Connections

• m-sequences offer flat Fourier properties suited to diffusion design #expands (0.85)
• A loudspeaker array’s polar pattern is a Fourier transform of its illumination #exemplifies (0.80)
• Frequency, phase, and impulse responses are interchangeable transforms of each other #expands (0.80)
• Optimal absorber placement requires flat-Fourier-transform weighting #expands (0.80) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2102
• Accurate square waves require infinitely many harmonics #exemplifies (0.75)