This pair of articles explains how the arhythmic quality of Sri Lankan Buddhist drum offerings is an intentional avoidance of Indian tala metrical theory in order to justify the drumming as as a kind of communal recitation appropriate to offer to the Buddha.

1. South Asian Drumming Beyond Tala: The Problem with “Meter” in Buddhist Sri Lanka
2. On the Sonic Materialization of Buddhist History: Drum Speech in Southern Sri Lanka
3. along with numerous Audio and Video examples.

In this way, we should view Sri Lankan Buddhist drumming not as a simple application of pre-Buddhist rites to a nominally Buddhist context but rather as a unique, and uniquely Buddhist, art form in its own right.