¥Out-of-tune piano: rapid beating results from nearby strings whose vibrations go in and out of phase
¥Rapid sequence of brief auditory events
¥Roughness most pronounced when sound includes spectrally coherent fluctuations
¥Can be minimized by randomizing the amplitudes and phases of its Fourier components
¥Randomization happens automatically in reverberant environments
¥Roughness reduction may be one of the benefits of adding reverb