Sesquialtera in the Colombian Bambuco: Perception and Estimation of Beat and Meter

The bambuco, one of the national rhythms of Colombia, is characterized by the presence of sesquialteras or the superposition of rhythmic elements from two meters. In this work, we analyze sesquialteras in bambucos from two perspectives. First, we analyze the perception of beat and meter by asking 10 Colombian musicians to perform beat annotations in a dataset of bambucos. Results show great diversity in the annotations: a total of five different meters or meter combinations were found in the annotations, with each bambuco in the study being annotated in at least two different meters. Second, we perform a beat tracking analysis in a dataset of bambucos with two state-of-the-art algorithms. Given that the algorithms used in the analysis were designed to deal with the rhythmic regularity of a single meter, it is not surprising that tracking performance is not very high ('42% mean F-measure). However, a deeper analysis of the onset detection functions used for beat tracking, indicate that there is enough information on the signal level to characterize the bi-metric behavior of bambucos. With this in mind, we highlight possibilities for computational analysis of rhythm in bambucos.