Masking can occur even when the masker follows the test sound in time.

Evidence

Masking effects can be measured not only when masker and test sound are presented simultaneously, but also when they are not simultaneous. In the latter case, the test sound has to be a short burst or sound impulse which can be presented before the masker stimulus is switched on. The masking effect produced under these conditions is called pre-stimulus masking, shorted to “pre masking” (the expression “backward masking” is also used). — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 399

Categorization

• DEFINE: Defines pre- or backward masking — masking when the masker is not simultaneous with the test sound.
• QUESTION: Backward masking where a later masker conceals an earlier stimulus is counterintuitive — worth investigating its neural mechanism.
• XREF: Connects to temporal processing theory and how delayed neural responses to the masker could overwrite the test tone’s trace.