Maria Panteli

Intersection based decentralized diagnosis: Implementation and verification

We consider decentralized diagnosis in discrete event systems that are modeled as non-deterministic finite automata and are observed, through distinct natural projection maps, at multiple observation sites. Specifically, we consider a scenario where two or more observers (each with its own map) are allowed to communicate their assessments (state estimates and matching normal/failure conditions) to a centralized location which then makes an overall decision based on the intersection of the local state estimates and their matching conditions. This intersection based decentralized diagnosis (IBDD) scheme can be implemented with polynomial complexity, both at the observation sites and at the centralized location. It is shown that IBDD can be verified with an algorithm of polynomial complexity that constructs verifiers for the observation sites, and analyzes properties of their parallel composition and product with the system.

A Quantitative Comparison of Chrysanthine Theory and Performance Practice of Scale Tuning, Steps, and Prominence of the Octoechos in Byzantine Chant

Abstract Byzantine Chant performance practice is computationally compared to the Chrysanthine theory of the eight Byzantine Tones (octoechos). Intonation, steps, and prominence of scale degrees are quantified, based on pitch class profiles. The novel procedure introduced here comprises the following analysis steps: (1) the pitch trajectory is extracted and post processed with music-specific filters. (2) Pitch class histograms are calculated by kernel smoothing. (3) Histogram peaks are detected. (4) Phrase ending analysis aids the finding of the tonic to align pitch histograms. (5) The theoretical scale degrees are mapped to the empirical ones. (6) A schema of statistical tests detects significant deviations of theoretical scale tuning and steps from the estimated ones in performance practice. (7) The ranked histogram peak amplitudes are compared to the theoretic prominence of particular scale degrees. The analysis of 94 Byzantine Chants performed by four singers shows a tendency of the singers to level theoretic particularities of the echos that stand out of the general norm in the octoechos: theoretically extremely large steps are diminished in performance. The empirical intonation of the IV. scale degree as the frame of the first tetrachord is more consistent with the theory than the VI. and the VII. scale degree. In practice, smaller scale degree steps (67–133 cents) appear to be increased and the highest scale step of 333 cents appears to be decreased compared to theory. In practice, the first four scale degrees in decreasing order of prominence I, III, II, IV are more prominent than the V., VI., and the VII..

Perception of timbre and rhythm similarity in electronic dance music

Music similarity is known to be a multi-dimensional concept, depending among others on rhythm similarity and timbre similarity. The present study aims to investigate whether such sub-dimensions of similarity can be assessed independently and how they relate to general similarity. To this end, we performed a series of web-based perceptual experiments on timbre, rhythm and general similarity in electronic dance music. Participants were asked to rate similarities of music pairs on a 4-point Likert scale. The results indicated that the ratings in the three types of similarity did not completely overlap and that participants showed slight to fair agreement in their ratings in all conditions. Together, the results suggest that it is possible to assess sub-dimensions of similarities independently to some extent. Interestingly, general music similarity was not completely explained by the summation of timbre and rhythm similarity. Based on this, a novel hypothesis of how general music similarity follows from its contributing sub-similarities is proposed.

A computational study on outliers in world music

The comparative analysis of world music cultures has been the focus of several ethnomusicological studies in the last century. With the advances of Music Information Retrieval and the increased accessibility of sound archives, large-scale analysis of world music with computational tools is today feasible. We investigate music similarity in a corpus of 8200 recordings of folk and traditional music from 137 countries around the world. In particular, we aim to identify music recordings that are most distinct compared to the rest of our corpus. We refer to these recordings as ‘outliers’. We use signal processing tools to extract music information from audio recordings, data mining to quantify similarity and detect outliers, and spatial statistics to account for geographical correlation. Our findings suggest that Botswana is the country with the most distinct recordings in the corpus and China is the country with the most distinct recordings when considering spatial correlation. Our analysis includes a comparison of musical attributes and styles that contribute to the ‘uniqueness’ of the music of each country.