The effect of stimulus intensity on the right ear advantage in dichotic listening

Neurosci Lett. 2008 Jan 24;431(1):90-4. doi: 10.1016/j.neulet.2007.11.046. Epub 2007 Dec 3.

Abstract

The dichotic listening test is non-invasive behavioural technique to study brain lateralization and it has been shown, that its results can be systematically modulated by varying stimulation properties (bottom-up effects) or attentional instructions (top-down effects) of the testing procedure. The goal of the present study was to further investigate the bottom-up modulation, by examining the effect of differences in the right or left ear stimulus intensity on the ear advantage. For this purpose, interaural intensity difference were gradually varied in steps of 3 dB from -21 dB in favour of the left ear to +21 dB in favour of the right ear, also including a no difference baseline condition. Thirty-three right-handed adult participants with normal hearing acuity were tested. The dichotic listening paradigm was based on consonant-vowel stimuli pairs. Only pairs with the same voicing (voice or non-voiced) of the consonant sound were used. The results showed: (a) a significant right ear advantage (REA) for interaural intensity differences from 21 to -3 dB, (b) no ear advantage (NEA) for the -6 dB difference, and (c) a significant left ear advantage (LEA) for differences form -9 to -21 dB. It is concluded that the right ear advantage in dichotic listening to CV syllables withstands an interaural intensity difference of -9 dB before yielding to a significant left ear advantage. This finding could have implications for theories of auditory laterality and hemispheric asymmetry for phonological processing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation / methods
  • Adult
  • Audiometry / methods
  • Auditory Cortex / physiology
  • Auditory Pathways / physiology
  • Dichotic Listening Tests / methods*
  • Ear / physiology*
  • Female
  • Functional Laterality / physiology*
  • Humans
  • Loudness Perception / physiology*
  • Male
  • Pitch Perception / physiology
  • Prohibitins
  • Sound Localization / physiology*