Cortical representation of vowels reflects acoustic dissimilarity determined by formant frequencies.

We studied neuromagnetic correlates of the processing of German vowels [a], [e] and [i]. The aim was (i) to show an influence of acoustic/phonetic features on timing and mapping of the N100 m component and (ii) to demonstrate the retest reliability of these parameters. To assess the spatial configuration of the N100 m generators, Euclidean distances between vowel sources were computed. Latency, amplitude, and source locations of the N100 m component differed between vowels. The acoustically most dissimilar vowels [a] and [i] showed more distant source locations than the more similar vowels [e] and [i]. This pattern of results was reliably found in a second experimental session after at least 5 days. The results suggest the preservation of spectral dissimilarities as mapped in a F(1)-F(2) vowel space in a cortical representation.