Intervals and Scales

[Extract]
Sounds that involve changes in pitch arise from a range of sources and provide
useful information about the environment. For humans, the most salient sources of pitch change come from speech and music. Speech includes rising and falling pitch patterns that characterize vocal prosody. These patterns signal the emotional state of the speaker, provide a source of linguistic accent, and indicate whether the speaker is asking a question or making a statement. Music also involves continuous pitch changes but more often involves discrete changes from one pitch level to another, called intervals. Sequences of intervals characterize the melodies in Western and non-Western music and can carry important structural, emotional and aesthetic meaning (Crowder, 1984; Narmour, 1983; Thompson, 2009). For both speech and music, relative changes in pitch are highly informative. Indeed, it is possible that pitch changes in these two domains are processed by overlapping mechanisms (Juslin & Laukka, 2003; Patel, 2008; Ross, Choi, & Purves, 2007; Thompson, Schellenberg, & Husain, 2004). Music has the added feature that it emphasizes a collection of discrete pitch categories, reducing the audible frequency continuum into a manageable number of perceptual elements and encouraging abrupt changes in pitch. Collections of discrete pitch categories, or scales, provide a psychological framework within which music can be perceived, organized, communicated,
and remembered.