Characterization and Melodic Similarity of A Cappella Flamenco Cantes! Joaquín Mora Francisco Gómez Emilia Gómez Department of Evolutive Applied Mathematics Department, Music Technology Group, and Educational Psychology School of Computer Science Universitat Pompeu Fabra University of Seville Polytechnic University of Madrid [email protected] [email protected] [email protected] Francisco Escobar-Borrego José Miguel Díaz-Báñez Department of Audiovisual Communication, Department of Applied Mathematics II, Publicity and Literature University of Seville University of Seville [email protected] [email protected] ABSTRACT On the other hand, research on music similarity has mainly focused on the analysis of music from the so- This paper intends to research on the link between musi- called "Western tradition", although there is an increasing cal similarity and style and sub-style (variant) classifica- interest in analyzing music from different traditions, and tion in the context of flamenco a cappella singing styles. some recent MIR studies are devoted to this issue [3]. Given the limitation of standard computational models In this paper we study the relationship between music for melodic characterization and similarity computation similarity and style definition in the context of a group of in this particular context, we have proposed a specific set flamenco a cappella singing styles. Because of its oral of melodic features adapted to flamenco singing styles. In transmission, formal classification and musical analysis order to evaluate them, we have gathered a collection of of flamenco present considerable difficulties. Classifica- music recordings from the most representative singers tion of styles is usually carried out by flamenco experts and have manually extracted those proposed features. and rests upon the analysis of the oral corpus of flamenco Based on those features, we have defined a similarity music. Flamenco experts have used several criteria in measure between two performances and have validated their classification, some of which, unfortunately, are not their usefulness in differentiating several styles and vari- fully explicit and clear-cut. Moreover, there exists con- ants. The main conclusion of this work is the need to in- siderable controversy among flamenco experts and at pre- corporate specific musical features to the design of simi- sent there is a lack of a unified, unequivocal classification larity measures for flamenco music so that flamenco- of a cappella cantes. adapted MIR systems can be developed. Our previous research has focused on analyzing the relationship between music similarity and style definition 1. INTRODUCTION from different perspectives, such as computational mod- els for melodic similarity [3] and human ratings of There is a wealth of literature on music research that fo- rhythmic patterns [6]. In Cabrera et al. [3], we applied cuses on the understanding of music similarity from dif- ferent viewpoints as well as the use of similarity dis- standard melodic similarity measures to a music collec- tances to cluster different pieces according to artist, genre tion of a cappella flamenco music. Extraction of melodic or mood. Over the past few years, the Music Information contours, although arduous, produced faithful descrip- Retrieval (MIR) community has been exploring several tions of cantes. However, when applied some standard ways to measure the similarity between two musical algorithms for comparing melodic contours (i.e. correla- pieces. They are often based on comparing musical ex- tion between pitch and interval histograms and edit dis- cerpts in audio format and computing the distance be- tance), we obtained rather poor results. Although global tween a representative set of their musical features (e.g., style classification seemed to work to some extent, fla- instrumentation, rhythmic patterns or harmonic progres- menco experts found that for variant classification of sions). This way, current systems can, for instance, locate some styles those algorithms failed to distinguish subtle, different versions of the same song with a high accuracy specific nuances of the cantes. We applied some cluster- rate [9]. ing techniques and it turned out that cantes that by musi- Alternative approaches are based on comparing con- cal reasons should be scattered were unexpectedly clus- textual information from the considered pieces or artists tered together. Thus, we concluded that further research (e.g., influences, temporal coincidences, geographical lo- had to be carried out. It soon became apparent that two cation), which is usually extracted from the web. A com- tasks, at least, had to be accomplished: first, to musically bination of these two approaches seems to be the most formalize the specific and subtle features of a cappella adequate solution [2], but there is still a glass ceiling on cantes; second, to refine our computational models ac- current systems. This seems to be owing to the fact that cording to those features. there are still fundamental musical features to be consid- This paper intends to research on the link between ered or fully incorporated into existing models [10]. musical similarity and style classification and sub-style (variant) definition in the context of flamenco a cappella Classification of a cappella cantes is subject to many dif- singing styles. The main contributions are (1) Identify ficulties. Two cantes belonging to the same style may relevant and specific features that characterize a given sound very different to an unaccustomed ear. In general, performance in the context of its style. Here, we consider underlying each cante there is a melodic skeleton. that each style is characterized by a prototypical melodic Donnier [4] called it the “cante’s melodic gene”. The contour. The features will then account for variations singer fills this melodic skeleton by using different kind within this contour. (2) Define a similarity measure based of melismas, ornamentation and other expressive re- on the identified features and provide an automatic sources. A flamenco aficionado recognizes two versions method of clustering and classification. (3) Evaluate the as to be the same cante because certain notes appear in results with a music collection of recordings from the certain order. What happens between two of those notes most representative performers and contrast them with does not matter regarding style classification, but does existing theories for the definition of styles and variants. matter for assessing a performance or the piece itself. This paper is organized as follows. In the next two Aficionado’s ears recognize the wheat from the chaff sections we analyze the characteristics of flamenco sing- when listening and appreciate a particular performance in ing and a cappella cantes. Next we give an overview of terms of the quality of the melodic filling, among other the cantes to be analyzed and we describe the music col- features. lection used in our study. We then present the set of fea- In order to put the reader in the position of un- tures that describes the two chosen cantes, namely, de- derstanding this point, in Figures 1 and 2 we show a tran- blas and martinetes. The following section deals with the scription of two versions of the same cante to Western similarity distance between cantes. A conclusion section musical notation. In this respect, Western notation has summarizes the main findings and presents some propos- been found limited for this kind of music (e.g. Donnier als for future research. [4] proposed the use of plainchant neumes). 2. FLAMENCO SINGING We now describe the main features that characterize fla- menco singing and differentiate it from other styles: - Instability of pitch. In general, notes are not clearly attacked. Pitch glides or portamenti are very common. - Sudden changes in volume (loudness). - Short pitch range or tessitura. It is normally limited to a major sixth interval and characterized by the insistence on a note and those contiguous. - Intelligibility of voices. Since lyrics are important in Figure 1: Manual transcription of a cante (debla). flamenco, there is a strong preference for intelligibility over range or timbre. Contralto and baritone voices are very common. - Timbre. Timbre characteristics of flamenco singers de- pend on the period in which it was performed. As rele- vant timbre aspects, we can mention breathiness in the voice and the absence of high frequency (singer) formant, which is characteristic of classical singing styles. From a musical point of view, a cappella cantes retain the following properties. Figure 2: Transcription of another version of the previous - Conjunct degrees. Melodic movement mostly occurs cante. by conjunct degrees. - Scales. Certain scales such as the dominant Phrygian 3. THE STYLES OF TONÁS mode (with a major tonic) and Ionian mode (E-F-G#-A- B-C-D) are predominant. As defined earlier, a cappella cantes are songs without - Ornamentation. There is also a high degree of complex instrumentation, or in some cases with some percussion ornamentation, melismas being one of the most signifi- (in the flamenco argon also cantes a palo seco). An im- cant devices of expressivity. portant group of such cantes is composed of tonás, style - Microtonality. The use of intervals smaller than the that generically include martinetes, deblas, saetas, tonás equal-tempered semitones of Western classical music is and carceleras. Since in flamenco music the word toná frequent. refers to both the style and one of its variants,