音樂即興，依作曲介入的程度，有層次的差別，越接近｢絕對作曲端」者，自由度越小；反之，越接近「絕對即興端」者，自由度越大。本文所討論的，係靠近「絕對即興端」的音樂，以客家八音絃索樂導奏、鋼琴前奏曲以及印度的阿拉普為例，透過跨樂種比較，深入観察不同文化的音樂所呈現即興的共通特質。

Freedom in musical performance can depend on the degree of “predetermined，， composition: “absolute composition，，implies a lesser degree of freedom in performance, whereas “absolute improvisation，seems to suggest the most freedom for the performer. This article discusses music closer to the point of “absolute improvisation，，which may arise at the point of performance. Various musical examples, including the introduction of the Hakka xiansuo bayin, a piano prelude, and the alap in India are analyzed and compared, in order to hopefully discover some common features of improvisation among these examples from diverse musical backgrounds.