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In music, ''additive'' and ''divisive'' are terms used to distinguish two types of both rhythm and meter. A divisive (or, more commonly, multiplicative) rhythm is a rhythm in which a larger period of time is divided into smaller rhythmic units or, conversely, some integer unit is regularly multiplied into larger, equal units; this can be contrasted with additive rhythm, in which larger periods of time are constructed by concatenating (joining end to end) a series of units into larger units of unequal length, such as a 5/8 meter produced by the regular alternation of 2/8 and 3/8 . When applied to meters, the terms "perfect" and "imperfect" are sometimes used as the equivalents of "divisive" and "additive", respectively (). For example, 4 may be evenly divided by 2 (4/2 = 2) or reached through repeatedly adding 2 (2 + 2 = 4), while 5 is only evenly divisible by 5 and 1 (5/2 = 2.5; 5/3 = 1.66) and may be reached by repeatedly adding 1 or 5 (2 + 2 = 4, 4 + 2 = 6; 3 + 3 = 6); thus 4/8 is divisive while 5/8 is additive. The terms additive and divisive originate with Curt Sachs's book ''Rhythm and Tempo'' (1953) , while the term ''akshak rhythm'' was introduced for the former concept at about the same time by Constantin , in agreement with the Turkish musicologist Ahmed Adnan Saygun . The relationship between additive and divisive rhythms is complex, and the terms are often used in imprecise ways. Justin London states in his article on rhythm in the second edition of the ''New Grove Dictionary of Music and Musicians'' that "In discussions of rhythmic notation, practice or style, few terms are as confusing or used as confusedly as ‘additive’ and ‘divisive’. … These confusions stem from two misapprehensions. The first is a failure to distinguish between systems of notation (which may have both additive and divisive aspects) and the music notated under such a system. The second involves a failure to understand the divisive and additive aspects of metre itself" . Winold recommends that, "metric structure is best described through detailed analysis of pulse groupings on various levels rather than through attempts to represent the organization with a single term" . Sub-Saharan African music and most European (Western) music is divisive, while Indian and other Asian musics may be considered as primarily additive. However, many pieces of music cannot be clearly labeled divisive or additive. ==Divisive rhythm== For example: 4/4 consist of one measure (whole note: 1) divided into a stronger first beat and slightly less strong second beat (half notes: 1, 3), which are in turn divided, by two weaker beats (quarter notes: 1, 2, 3, 4), and again divided into still weaker beats (eighth notes: 1 & 2 & 3 & 4 &). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Additive rhythm and divisive rhythm」の詳細全文を読む スポンサード リンク
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