Objective measures of musical tempo are linked to a particular metrical pulse, and this is most likely true for subjective tempo as well. Therefore, tapping along with a rhythm should be predictive of relative tempo judgments. The difficulty of such judgments may lie in the choice of a particular metrical level as the referent. Multiple levels may compete and create ambiguity. Analogies are drawn with pitch perception from certain types of complex tones.Submitted 2011 January 19; accepted 2011 February 14. KEYWORDS: tempo, meter, tactus, tapping, pitch, timbre LONDON (2011) has made an interesting empirical contribution to the study of tempo judgment. He asked participants to compare the tempi of simple isochronous rhythms in which one or two higher metrical levels were highlighted by regularly recurring pitch accents. When two different rhythmic patterns were presented in succession, participants often did not make their judgments according to the tempo of the nominal tactus (the quarter note). London's main conclusion is that "our perception of musical speed or tempo is more than simple apprehension of the tactus rate" (p. 1). Does he mean the nominal tactus rate or any tactus rate?
NOMINAL VERSUS SUBJECTIVE TACTUSThe rate of the nominal tactus of his materials (100 or 120 beats per minute) was chosen to be in the most preferred region for a musical beat (Parncutt, 1994;van Noorden & Moelants, 1999). However, that does not guarantee that participants would always choose the nominal tactus as the most salient metrical level. The subjective tactus might differ, especially when higher metrical levels carry regular pitch accents. Indeed, in his Experiment 3, where participants were required to tap along with each rhythm, London found that they did not always tap with the nominal tactus. Presumably, they tapped with their subjective tactus.One reasonable conjecture then is that participants made their tempo judgments according to their subjective tactus, regardless of whether they did or did not tap along with it. London found that instructions to "focus on the beat rate" (p. 3, Experiment 2) or "tap along with the beat" (p. 4, Experiment 3) had relatively little effect on participants' tempo judgments. From his description it seems he did not instruct participants to focus on or tap along with the quarter-note beat, only with "the beat." That beat then was most likely the subjective tactus, and if it already formed the basis of tempo judgments in Experiment 1, then it is understandable that focusing on or tapping along with it had little additional effect.If my conjecture is right, then the tempo judgments in Experiment 3 should have been consistent with the tapping tempi. Although London examined these tempi and related them to different metrical levels, he does not report how they related to the tempo judgments. If participants tapped faster to one rhythm than to another on any given trial, did they always (or nearly always) judge the tempo of the former to be faster than the tempo of the latter? Th...