The pentatonicity of two bevelled bamboo flutes from Obo of South Cotabato and Maguindanao, Philippines

Abstract

Indigenous Philippine bamboo flutes lack a precise manufacturing process, resulting in variations in tuning. Despite this, these flutes share a common musical attribute: they follow a pentatonic scale. Using Spectrogram analysis, this study aims to confirm the pentatonicity of Philippine indigenous bamboo flutes by calculating the ratio of their fundamental frequencies. We extracted audio characteristics from four video performances of an Obo notched flute in South Cotabato, Philippines. This method of analysis is useful in instances where only recorded performances of the instrument are available. The obtained frequency ratios were then compared with two external datasets containing single-note performances of other versions of bamboo flutes. We report the presence of the pentatonic ratio in all examined bamboo flute performances. This quantitative analysis confirmed that the recorded Obo flute performance of a Manobo flutist followed a pentatonic scale at approximately the following notes: D4 (300 Hz), E4 (330 Hz), F#4 (370 Hz), A4 (440 Hz), and B4 (500 Hz).