In order to determine the neural substrates of phonemic coding during both listening and speaking, we used a repetition suppression (RS) paradigm in which vowels were repeatedly perceived or produced while measuring BOLD activity with sparse sampling functional magnetic resonance imaging (fMRI). RS refers to the phenomenon that repeated stimuli or actions lead to decreased activity in specific neural populations associated with enhanced neural selectivity and information coding efficiency. Common suppressed BOLD responses during repeated vowel perception and production were observed in the inferior frontal gyri, the posterior part of the left middle temporal gyrus and superior temporal sulcus, the left intraprietal sulcus, as well as in the cingulate gyrus and presupplementary motor area. By providing evidence for common adaptive neural changes in premotor and associative auditory and somatosensory brain areas, the observed RS effects suggest that phonemic coding is partly driven by shared sensorimotor regions in the listening and speaking brain.