Masking is quantified as the threshold shift between unmasked and masked conditions.

Evidence

The amount of masking is typically measured using two conditions: an unmasked condition and a masked condition. The unmasked condition is essentially the same as detection in quiet, akin to measuring absolute threshold. In the masked condition, the threshold for the same stimulus is then measured in the presence of the masker. … In a masking experiment, one interval contains the masker and signal, whereas the other interval contains the masker alone. The listener then selects which of these two intervals contains the signal. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 442

The amount of masking is typically measured using two conditions: an unmasked condition and a masked condition. The unmasked condition is essentially the same as detection in quiet, akin to measuring absolute threshold. In the masked condition, the threshold for the same stimulus is then measured in the presence of the masker. Many experiments measured masking using simultaneous masking, a paradigm in which the signal and masker completely overlap in time. The masker may start prior to and end after the signal, but the entirety of the signal must fall within the duration of the masker stimulus. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 442

Categorization

• DEFINE: Defines the standard two-condition masked/unmasked measurement protocol and the 2I-2AFC masking trial design.
• corroborated: 2 independent passages support this claim — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 442