Decorrelators degrade audio quality on transient-rich signals like applause.

Evidence

There are various implementations of decorrelators. A typical approach is to alter the time or phase structure of the signal over a short time interval. Examples of such processes are different delays in frequency bands, all-pass filters, and convolutions with short noise sequences. It is widely known in the field that decorrelators can cause degradation of the perceived sound quality with certain signal content such as applause (Kuntz et al., 2011; Laitinen et al., 2011), because, as a consequence of the decorrelation, the sharp temporal structure of the signal is altered. Applications employing decorrelators thus often apply specific processes to avoid or reduce such effects, for example, with onset detectors that bypass transients from the decorrelators. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 2151

Categorization

• DEFINE: Defines what decorrelators do (alter time/phase structure per frequency band) and precisely why they fail on applause-like content.
• XREF: Links to spatial audio/spatialization applications where decorrelation is used to widen sound; the applause failure case is the classic test signal in psychoacoustics.