Tuning of human modulation filters is carrier-frequency dependent

PLoS One. 2013 Aug 29;8(8):e73590. doi: 10.1371/journal.pone.0073590. eCollection 2013.

Abstract

Recent studies employing speech stimuli to investigate 'cocktail-party' listening have focused on entrainment of cortical activity to modulations at syllabic (5 Hz) and phonemic (20 Hz) rates. The data suggest that cortical modulation filters (CMFs) are dependent on the sound-frequency channel in which modulations are conveyed, potentially underpinning a strategy for separating speech from background noise. Here, we characterize modulation filters in human listeners using a novel behavioral method. Within an 'inverted' adaptive forced-choice increment detection task, listening level was varied whilst contrast was held constant for ramped increments with effective modulation rates between 0.5 and 33 Hz. Our data suggest that modulation filters are tonotopically organized (i.e., vary along the primary, frequency-organized, dimension). This suggests that the human auditory system is optimized to track rapid (phonemic) modulations at high sound-frequencies and slow (prosodic/syllabic) modulations at low frequencies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation
  • Adult
  • Auditory Cortex / physiology*
  • Auditory Perception / physiology*
  • Female
  • Humans
  • Male
  • Perceptual Masking
  • Young Adult

Grant support

The first author was supported by an EPSRC (http://www.epsrc.ac.uk/) DTA studentship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.