ABSTRACT
The classification of objects into categories appears to be a universal preoccupation of human beings all over the world. Besides seeming to provide untold pleasures in creating order around us, classication assists us in an uncountable number of more specic ways. For one, it improves our ability to remember large amounts of information. It aids librarians to catalogue musical material for archiving and e ciently retrieving information.* It helps doctors prescribe the right medication if they classify a patient’s disease correctly. In the domain of music, musicologists classify almost everything they can: musical instruments,† drum sounds,‡ music notes on score sheets,§ music patterns,¶ folk tunes,** scales,†† chords,‡‡ keys,§§ meters,¶¶ spans,*** complexity classes of meters,††† rhythms,‡‡‡ Indian talas,§§§ melodies,¶¶¶ contours,****
genres, styles, dance music,‡ and other types of music. Clearly, classication is a primary concern in almost all aspects of music. For each of these applications, there exist suitable features, and a variety of tools available for classication. Simha Arom classies the family of aksak rhythms from the Balkan region into three classes depending on the properties of the number of pulses contained in the rhythm’s cycle.¶ All aksak rhythms are composed of a string of interonset durations of lengths two and three, which Arom calls binary and ternary cells. He calls an aksak rhythm authentic provided that its pulse number is a prime number. Some authentic aksak rhythms include [2-3], [2-2-3], and [2-2-2-3-2-2], with pulse numbers 5, 7, and 13, respectively. A rhythm is quasi-aksak, provided that its pulse number is odd, not prime, and divisible by three. Some instances of quasi-aksak rhythms are [2-2-2-3] and [2-2-2-2-3-2-2], with pulse numbers 9 and 15, respectively. Finally, a rhythm is called pseudo-aksak if its pulse number is even. us, the rhythms [2-3-3], [2-2-3-3], and [2-2-2-3-3], with pulse numbers 8, 10, and 12, respectively, are pseudo-aksak. Arom lists 33 conrmed and documented aksak rhythms that are played in practice, that have pulse numbers ranging from 5 to 44, excluding the numbers 6, 20, 31, 36, 38, 40, and 43. In this chapter, I illustrate several general approaches to solving the problem of classication, by using the six distinguished timelines as a pedagogical toy exemplar.
