The aim of this study was to determine if two dimensions of song, the phonological part of lyrics and the melodic part of tunes, are processed in an independent or integrated way. In a series of five experiments, musically untrained participants classified bi-syllabic nonwords sung on two-tone melodic intervals. Their response had to be based on pitch contour, on nonword identity, or on the combination of pitch and nonword. When participants had to ignore irrelevant variations of the non-attended dimension, patterns of interference and facilitation allowed us to specify the processing interactions between dimensions. Results showed that consonants are processed more independently from melodic information than vowels are (Experiments 1-4). This difference between consonants and vowels was neither related to the sonority of the phoneme (Experiment 3), nor to the acoustical correlates between vowel quality and pitch height (Experiment 5). The implication of these results for our understanding of the functional relationships between musical and linguistic systems is discussed in light of the different evolutionary origins and linguistic functions of consonants and vowels. (Contains 7 tables and 5 figures.)