Tonality Without Structure: Using Drones to Induce Modes and Convey Moods

In most Western music, notes in a melody relate not only to each other, but also to a “key”—a tonal center combined with an associated scale. Music is often classified as in a major or minor key, but within a scale that defines a major key, emphasizing different notes as the tonic yields different “modes.” Thus, within a set of notes, changing the tonal center changes the putative role of any given note. In this experiment, we eliminated all structural cues to the tonic within a melody by presenting notes randomly selected from the C major scale. A “mode” was established by a continuous drone note lower than the melody. Subjects rated mood (happy versus sad) and tension of each pseudo-melody. Consistent with Temperley and Tan (2013)—in which multiple structural cues were present—different modes produced reliable differences in judged mood and tension. Notably, modes with a major 3rd from the tonic (Ionian, Lydian, Mixolydian) were perceived as happier and less tense than modes with a minor 3rd (Dorian, Aeolian, Phrygian, Locrian). The results confirm that the perception of notes in a melody, and their consequent emotional connotation, depend at least in part to their relationship to a tonal center.