Simultaneous masking yields broader tuning curves than forward masking.
Evidence
Measuring PTCs under forward and simultaneously masked conditions illustrates why we must consider both situations. Moore, Glasberg, and Roberts (1984) measured PTCs for a tone presented at 10 dB SL and at four different frequencies under both simultaneous and forward masked conditions. They found that that simultaneousand forward-masked PTCs have a very similar shape, as shown in Figure 3–15. However, we see a striking difference between the two types of PTCs. The PTC measured using simultaneous masking was broader than the PTC measured using forward masking. We also observe evidence of upward spread of masking in the shallower low-frequency tail in both simultaneousand forward-masked conditions, suggesting that upward spread of masking is a robust property of the auditory system. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 532
Categorization
- QUESTION: Why is the simultaneous-masked PTC broader? The text gestures at nonlinear processing but doesn’t fully spell out the mechanism here — worth chasing in Moore, Glasberg, and Roberts.
- corroborated: 2 independent passages support this claim — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 532
- XREF: connects to: Masked threshold shape changes with masker level, becoming more asymmetric at high levels; A suppressor below masker threshold can reduce forward masking without itself masking the signal — Dijk, Pim van, Physiology, Psychoacoustics and…, 940; Forward masking avoids the nonlinear effects that only arise from simultaneity. (+1 more)