Auditory cortical activation in Finnish and Swedish speaking Finns: a magnetoencephalographic study.

To study the effects of linguistic background on auditory processing, magnetoencephalographic responses for pure tones (120 Hz, 1 and 4 kHz), [u] and a complex tone (with three pure tone components corresponding to the three lowest formant frequencies of [u]) were recorded in ten Finnish and ten Swedish speaking Finnish males. Auditory cortical activation, maximal at about 100 ms after stimulus onset, was stronger in the right hemisphere (RH) for all stimuli. At 175-225 ms, Swedish speaking subjects had larger inter-hemispheric differences and different signal morphology in the RH than Finnish speaking subjects, suggesting that linguistic background influences basic auditory processes. Possibly, Swedish speaking subjects had retained a juvenile response component due to their bilingual surrounding after early childhood.