Abstract
Effects of phase curvature in forward masking by Schroeder-phase harmonic tone complexes have been attributed to the interaction between the phase characteristics of the masker and the basilar-membrane (BM) filter, and to BM compression. This study shows that some of these effects may rely on additional mechanisms that have not been previously considered. First, the effect of masker phase curvature was observed for a masker with components well below the signal frequency that was presumably processed without compression by the BM filter. Second, the magnitude of the effect of masker phase curvature depended on masker duration, for durations between 30 and 200 ms. A model implementing the time course and level dependence of the medial olivocochlear reflex (MOCR) produced predictions consistent with the data from masking by on- and off-frequency Schroeder-phase maskers. The results suggest that MOCR effects may play a greater role in forward masking than previously thought.
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Acknowledgments
This work was supported by grant R01 DC 03909 from the National Institutes of Health. We thank Amy Olund for her help with data collection. These data and the model predictions are also reported in Wojtczak and Oxenham (2009).
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Wojtczak, M., Oxenham, A.J. (2010). Mechanisms of Masking by Schroeder-Phase Complexes. In: Lopez-Poveda, E., Palmer, A., Meddis, R. (eds) The Neurophysiological Bases of Auditory Perception. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-5686-6_4
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DOI: https://doi.org/10.1007/978-1-4419-5686-6_4
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