Daniel Shanahan

Eyebrow movements and vocal pitch height: Evidence consistent with an ethological signal

When asked to sing a high pitch, people produce a facial expression that is judged more friendly compared with singing a low pitch [Huron et al. (2009). Empirical Musicology Rev. 4(3), 93-100]. This effect was observed even when judges viewed only the face above the tip of the nose, and implies a relationship between pitch height and eyebrow height. In the current study, we examine the reverse relationship. Thirty-one participants were asked to read aloud standard texts while holding their eyebrows in a raised, neutral, or lowered position. Average F0 was found to correlate positively with eyebrow position, with higher vocal pitch associated with higher eyebrow placement. However, manipulating eyebrow placement produces a considerably smaller effect (on pitch) compared with the effect of manipulating pitch (on eyebrows). Results are discussed from the perspective of ethological signals [Lorenz (1939). Zool. Anz. 12, 69-102].

The sounds of safety: stress and danger in music perception

As with any sensory input, music might be expected to incorporate the processing of information about the safety of the environment. Little research has been done on how such processing has evolved and how different kinds of sounds may affect the experience of certain environments. In this article, we investigate if music, as a form of auditory information, can trigger the experience of safety. We hypothesized that (1) there should be an optimal, subjectively preferred degree of information density of musical sounds, at which safety-related information can be processed optimally; (2) any deviation from the optimum, that is, both higher and lower levels of information density, should elicit experiences of higher stress and danger; and (3) in general, sonic scenarios with music should reduce experiences of stress and danger more than other scenarios. In Experiment 1, the information density of short music-like rhythmic stimuli was manipulated via their tempo. In an initial session, listeners adjusted the tempo of the stimuli to what they deemed an appropriate tempo. In an ensuing session, the same listeners judged their experienced stress and danger in response to the same stimuli, as well as stimuli exhibiting tempo variants. Results are consistent with the existence of an optimum information density for a given rhythm; the preferred tempo decreased for increasingly complex rhythms. The hypothesis that any deviation from the optimum would lead to experiences of higher stress and danger was only partly fit by the data. In Experiment 2, listeners should indicate their experience of stress and danger in response to different sonic scenarios: music, natural sounds, and silence. As expected, the music scenarios were associated with lowest stress and danger whereas both natural sounds and silence resulted in higher stress and danger. Overall, the results largely fit the hypothesis that music seemingly carries safety-related information about the environment.

Supervised descriptive pattern discovery in Native American music

The discovery of recurrent patterns in groups of songs is an important first step in computational corpus analysis. In this paper, computational techniques of supervised descriptive pattern discovery are applied to model and extend ethnomusicological analyses of Native American music. Using a corpus of over 2000 songs collected and transcribed by anthropologist Frances Densmore and building on Densmore’s own music content features, the analysis identifies musical differences between indigenous groups and between musical style areas of the North American continent. Contrast set mining is adapted to discover global-feature patterns which are distinctive for a group, statistically significant and maximally general. The work extends previous descriptive studies in computational folk music analysis by considering feature-set patterns of variable size. Discovered patterns confirm, differentiate and complement ethnomusicological observations on Native American music.