Abrupt level changes create audible clicks via broad short-time spectra.

Evidence

Abruptly changing the sound pressure or the sound pressure level of a sinusoidal tone leads to a sensation that may contain not only an audible change in level but also the sensation of a click at the time of the abrupt change. The abrupt change produces a short-time spectrum that is relatively broad, the reason for the audible click. To avoid clicks, just-noticeable amplitude variations are often measured by amplitude modulation. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1005

Categorization

• XREF: Connects to the reader’s broader interest in psychoacoustic models and spectral analysis; relates to how transient phenomena map onto perception, echoing earlier chapters’ treatment of temporal and spectral loudness effects.
• corroborated: 2 independent passages support this claim — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1005