Interferers partially rather than fully suppress the modulation cues used for detection

Evidence

In a previous study (van de Par et al. 2012 ), this monaural explanation was tested by attempting to reduce the effectiveness of the modulation cues by creating a Modulation Detection Interference (MDI) effect. To this end a tonal interferer was provided at the opposite spectral side of the masker compared to where the target was, but with the same spectral distance between target and masker as between masker and interferer. This extra interferer created beating frequencies that were equal to those that should be created by the presence of the target tone. Although these beating frequencies are then present in different auditory channels, the across-frequency nature of MDI (Yost et al. 1989 ) implies that they should still interfere with the modulation cues used for detecting the target tone. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3467

This indicates that the present approach was too simplistic, i.e., modulation cues may only be reduced and not abolished by the presence of the interferer. In addition, not only modulation frequencies close to the beating frequency may be affected by the presence of the interferer but also other modulation frequencies. This is also consistent with MDI results where an MDI is also observed for modulation frequencies of the interferer that differ from the target modulation frequency (Yost et al. 1989 ). A better match between data and simulations could be achieved by assuming weights to the output of the modulation filters that gradually increase as the distance between beating frequency (masker—interferer) increases. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3463

The second model assumed that modulation cues with frequencies adjacent to the beating frequency between interferer and masker could not be used for signal detection. … This indicates that the present approach was too simplistic, i.e., modulation cues may only be reduced and not abolished by the presence of the interferer. In addition, not only modulation frequencies close to the beating frequency may be affected by the presence of the interferer but also other modulation frequencies. … A better match between data and simulations could be achieved by assuming weights to the output of the modulation filters that gradually increase as the distance between beating frequency (masker—interferer) increases. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3497

Categorization

• DEFINE: Explains what Modulation Detection Interference (MDI) is and its across-frequency property.
• QUESTION: The gradually-weighted modulation filterbank idea is underspecified here — worth chasing how weights would be derived and whether they predict MDI data.
• corroborated: 3 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 3467; Dijk, Pim van, Physiology, Psychoacoustics and…, 3463; Dijk, Pim van, Physiology, Psychoacoustics and…, 3497