 Sotorrio argues that fixed-do is preferable for serious musicians, as music involving complex modulations and vague tonality is often too ambiguous with regard to key for any movable system.That is, without a prior analysis of the music, any movable-do system would inevitably need to be used like a fixed-do system anyway, thus causing confusion.With fixed-do, the musician learns to regard any syllable as the tonic, which does not force them to make an analysis as to which note is the tonic when ambiguity occurs.