ABSTRACT
The emergent pattern of expectational peaks, foothills, and valleys brought about by layers of nested expectations gives rise to what experience as meter in music, and is encoded in music notation via a number of symbolic systems such as time signatures and note durations. There are few musical terms used more commonly, yet less precisely, than beat and tempo. London summarizes relevant research and creates "Tempo-Metrical Types" that map out the ramifications of tempo for not just tactus but for entire metric structures. Tempo is another term ubiquitous in music that is used in inconsistent and poorly defined ways. Some research has pointed to a tempo "sweet spot" in the middle of this tempo window, anywhere from 100 to 140 beats per minute (BPM). The simplest notion of beat and tempo revolves around the idea of an optimal range for tempo, centered on 100 BPM or 120 BPM.
