From Music Ontology Towards Ethno-Music-Ontology
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FROM MUSIC ONTOLOGY TOWARDS ETHNO-MUSIC-ONTOLOGY Polina Proutskova1 Anja Volk2 Peyman Heidarian3 György Fazekas1 1 Center for Digital Music, Queen Mary University of London, UK 2 Department of Information and Computing Sciences, Utrecht University, Netherlands 3 Department of Computer Science The University of Waikato, NZ [email protected], [email protected] ABSTRACT sual knowledge about the entities and their relationships in an area, preferably expressed using a machine-processable This paper presents exploratory work investigating the formal language that supports some form of inference [12]. suitability of the Music Ontology [33] - the most widely This could be logic based, while more recently, ontologies used formal specification of the music domain - for mod- found their use in machine learning as a mechanism to help elling non-Western musical traditions. Four contrasting structuring training data, formalise constraints, or become case studies from a variety of musical cultures are anal- an integral part of the inference process [42]. ysed: Dutch folk song research, reconstructive perfor- The Music Ontology (MO) [32, 33] is among the most mance of rural Russian traditions, contemporary perfor- comprehensive ontologies for the music domain, with mance and composition of Persian classical music, and broad ranging applications [9, 38] from recommendation recreational use of a personal world music collection. We systems [49] to live performance [51], and numerous ex- propose semantic models describing the respective do- tensions covering music production [10, 11] and audio ef- mains and examine the applications of the Music Ontology fects [53, 54], audio features [1], music theoretical con- for these case studies: which concepts can be successfully cepts [34, 43, 46], smart instruments and more generic or reused, where they need adjustments, and which parts of other “Musical Things” [48]. The ontology is based upon the reality in these case studies are not covered by the Mu- several broadly accepted domain models (see Section 2) sic Ontology. The variety of traditions, contexts and mod- adopted to the music domain. Moreover, it has been ap- elling goals covered by our case studies sheds light on the plied successfully to model jazz [31], a tradition distinct generality of the Music Ontology and on the limits of gen- from Western classical and pop music; and it was found to eralisation “for all musics” that could be aspired for on the be beneficial for modelling Chinese musical tradition due Semantic Web. to its flexibility and layered structure [45]. This makes it a primary candidate for our analyses. 1. INTRODUCTION The Music Ontology makes general claims about rep- Non-Western musical traditions are of interest to MIR re- resenting discographic information, music creation, per- search for several reasons: firstly, alongside Western clas- formance, production and consumption. Yet it has so far sical and popular music, which have been studied exten- mainly been applied to Western music. MIR researchers sively in MIR, the musics of other cultures are analysed with expertise in ethnomusicology [29, 50] suggest that in their own right [6, 13, 16, 25]; secondly, other musical computational approaches to non-Western music should all cultures often present difficult, non-standard datasets and be culture and use case specific. We therefore aim to an- examples, showing the limits of existing MIR approaches swer the following questions: Is the Music Ontology ca- [22, 30, 39]; finally, including non-Western musical tradi- pable of representing the domains of non-Western musi- tions allows for a broader view of music and leads to new, cal traditions? What are the gaps that the Music Ontol- more generally applicable technical solutions [24, 28, 40]. ogy fails to model? Can or should the Music Ontology be In this paper, we explore the latter avenue with the view generalised to encompass many (or all) musical traditions? of generalising existing standards of semantic modelling What are the limits of such generalisation? in music to include non-Western musical traditions. While political and geographic borders, language and Ontology in computer science is commonly defined as religion play an important role in forming musical tradi- an “explicit formal specification of a shared conceptualisa- tions, modelling the domain of such a tradition goes far tion of a domain ” [15]. An ontology represents consen- beyond adding a geo location. For instance, Kurdish music in northern Iraq is different from Kurdish music in Iran and Turkey; Persian musics in Iran, Afghanistan and Tajikistan c Polina Proutskova, Anja Volk, Peyman Heidarian, are also different, even though people speak in the same György Fazekas. Licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0). Attribution: Polina Proutskova, language (Persian); likewise Azerbaijan and Armenia have Anja Volk, Peyman Heidarian, György Fazekas. “From Music Ontology different religions and languages, but their musics are very towards Ethno-Music-Ontology”, 21st International Society for Music In- close. Also, music of a diaspora sometimes adheres closely formation Retrieval Conference, Montréal, Canada, 2020. to the original traditions and sometimes fuses with the mu- sic of the host community, importing new elements and establishing new trends. In addition to differences in musical systems and reper- toires, how people create, perform and listen to music varies between cultures. To account for this diversity, we chose four case studies from a variety of musical traditions. The use cases are representative of the chosen traditions, based on authors’ expertise as practitioners, researchers and consumers of those musical cultures. While by no means exhaustive, this investigation employs a qualitative approach to test the usefulness and representativeness of Figure 1. FRBR conceptual model. The shape and colour the Music Ontology in a large variety of contexts outside coding exemplified here is used throughout this paper to of Western classical and popular music. indicate classes implementing FRBR concepts First, we look at a Dutch state institution collecting folk songs of a tradition now largely extinct and how research (a distinct intellectual or artistic creation) and expression on this collection is conducted (Sec. 3). Secondly, contem- (the intellectual or artistic realisation of a work) reflect in- porary performance and composition in Iranian music are tellectual or artistic content. Manifestation (the physical explored, encompassing Persian classical art music, folk embodiment of an expression) and item (a single exem- music of many Iranian population groups and Western in- plar of a manifestation) reflect physical form.” Group 2 fluences (Sec. 4). Thirdly, we take the genre of world mu- includes persons and corporate bodies responsible for the sic into consideration, where recording and consumption custodianship of Group 1 intellectual or artistic endeavours are broadly in line with Western popular music (Sec. 5). (e. g., creators, consumers). Group 3 includes events and Additionally, we turn to Russian village music and how it places [17] (Fig. 1). is being actively revived through field research and perfor- The Music Ontology [32] provides a vocabulary for mance (see Supplement 1 ). publishing and linking a wide range of music-related data Dutch folk songs are a representative of folk music on the Web 2 . It builds on four main ontologies: FRBR traditions of Western Europe and North America in our Ontology 3 (Fig. 1), the Timeline Ontology 4 , the Event study; Russian village music is a polyphonic vocal tradi- Ontology 5 and FOAF 6 . Fig. 2 illustrates how the Mu- tion, which are common throughout Eastern Europe, and sic Ontology classes implement FRBR. It has been ex- are found in other parts of the world. Iranian music is a tended to describe a variety of musical domains, such as maqamic tradition, strongly connected to the modal tradi- audio content (Audio Features Ontology 7 [1]), recording tions encompassing the Near East, North Africa, and South sessions (Studio Ontology 8 [10]) and exploration, trans- Asia. The world music genre does not represent any par- formation and redistribution of audio content (AudioCom- ticular culture and can include all kinds of musical content mons Ontology 9 [4]). The Jazz Ontology [31] is a se- from around the world. mantic model successfully developed on the basis of MO. To illustrate how the Music Ontology (MO) classes and It illustrates how the Music Ontology requires "tweaking" properties can or cannot be used to model our case stud- with shortcuts, new or qualified properties and some addi- ies, we introduced a consistent form- and colour coding tional concepts to describe a musical tradition other than throughout this paper: MO classes and their subclasses Western popular or classical music. have solid line borders while other classes have dashed line MusicBrainz 10 is the largest crowd-sourced collection borders; MO properties are thick blue arrows with straight of music metadata online. It has its own semantic model heads; properties not present in the Music Ontology are [18], focused on discographic information about published thin red. CDs, therefore less suitable to musical traditions which are not centred around published products. 2. PREVIOUS WORK Tian et al. [45] presented a detailed analysis of metadata standards in existence in 2013, including the Music Ontol- The main standard for semantic modelling in cultural