On hearing a sequence of pitches, listeners develop expectations for how that sequence will continue. Research on melodic continuation generally supposes two kinds of factors: the top-down influence of perceived tonality, and the bottom-up influence of melodic contour (relative size and direction of the intervals). For bottom-up, contour-based factors, there is converging evidence that melodies with good continuation tend to have small intervals between notes and narrow overall ranges. Since melodic contour can also be perceived in sequences of notes varying in brightness (an aspect of timbre or sound quality) or loudness instead of pitch, it is reasonable to suppose that the same contour-based expectations that apply to pitch sequences also apply to brightness and loudness sequences. The present study found that perceptive continuation ratings for brightness and loudness sequences generally conform to the same contour-based expectations as pitch sequences, though some differences between dimensions were found.
This is compatible with the hypothesis that perception of melodic contour is a general auditory phenomenon that is not unique to pitch. The ratings for brightness and loudness sequences were more similar to each other than to ratings for pitch sequences, and it is likely that the factors that set pitch apart from other auditory dimensions are closely related to perceived tonality.