Comparative Analysis of A Cappella Flamenco Cantes

Comparative Melodic Analysis of A Cappella Flamenco Cantes Juan J. Cabrera Department of Applied Mathematics, School of Engineering, University of Seville, Spain juacabbae@us.com Jose Miguel Díaz-Báñez Department of Applied Mathematics, School of Engineering, University of Seville, Spain dbanez@us.es - http://www.personal.us.es/dbanez Francisco J. Escobar-Borrego Department of Audiovisual Communication, Publicity and Literature, University of Seville, Spain fescobar@us.es Emilia Gómez Music Technology Group, Universitat Pompeu Fabra, Barcelona, Spain egomez@iua.upf.edu - http://mtg.upf.edu/~egomez Francisco Gómez Applied Mathematics Department, School of Computer Science, Polytechnic Univ. of Madrid, E-mail: fmartin@eui.upm.es Joaquín Mora Department of Evolutive and Educational Psychology, University of Seville, Spain mora@us.es In: C. Tsougras, R. Parncutt (Eds.) Proceedings of the fourth Conference on Interdisciplinary Musicology (CIM08) Thessaloniki, Greece, 2-6 July 2008, http://web.auth.gr/cim08/ Background in ethnomusicology and music analysis. A cappella singing styles (called cantes in the flamenco jargon) are among the most fundamental song styles within the flamenco repertoire. Until very recently, flamenco singers have been only using oral transmission to learn them. Because of this form of diffusion, melody has become one of the main musical facets to be listened to, remembered, elaborated and spread in flamenco singing styles. Moreover, melody has helped flamenco enthusiasts to remember and identify variants of a particular style or genre. A frequent discussion and unanswered question among flamenco scholars is how to quantify the similarity between two melodies, and how to use this similarity measure to differentiate different styles and variants among performers, and to study the roots and evolution of flamenco styles. Background in computing, mathematics and statistics. State of the art techniques in melodic analysis of audio allow us to obtain different representation levels of a music recording (Gómez et alt. 2003). There are different representation levels for melody. Energy (intensity) and fundamental frequency (pitch) curves are the main low-level melodic features. In a higher structural level, note duration and pitch provide a symbolic representation, which can be the input to higher-level analyses. Finally, deviations of the analyzed recording with respect to the obtained score are related to expressivity. There have been some attempts to apply these techniques to the analysis of flamenco music (Donnier 1997, Gómez and Bonada 2008). There also a corpus of research on how to measure similarity between melodies using computational models, which are usually inspired in methods for string comparison (Crawford et alt. 1998, Mongeau and Sankoff 1990). Aims. After some previous studies on rhythmic similarity of flamenco styles (Díaz-Bañez et alt. 2004), the aim of this work is to compare different approaches of melodic and tonal analysis of flamenco a capella singing styles. The ultimate goal is to perform a multidisciplinary analysis that will provide us with tools to compare different versions of the same style, and, as a consequence, to clarify the roots of styles and their evolution. We contrast historical knowledge, we carry out manual melodic and tonal analysis assisted with automatic melodic description tools. In order to achieve this goal, it is also necessary to gather a representative musical corpus, a significantly difficult task due to the variety of media (mostly vinyl and magnetic tapes) and poor quality of existing flamenco recordings. Main contribution. One of the main contributions of this work is to gather a representative music collection for this study. The corpus was found on very diverse media (mostly vinyl and magnetic tapes), and comprises recording from the 40’s up to day. We have considered a music collection of songs without instrumentation or in some cases with some percussion, known in flamenco music as cantes a palo seco. This corpus is composed of two main styles, namely: martinetes and tonás. In total, there are 135 monophonic voice pieces covering the most representative flamenco singers. Musicological and historical criteria were followed when selecting the pieces. As a second step, we have performed different analysis of this music collection. From a musical and computational perspective, we first define a melodic representation capable of coping with the relevant subtleties of this kind of style, characterized by ornamentations. This melodic representation is automatically computed from the selected phrases (Gómez and Bonada 2008). Critical issues have risen regarding the location of the main notes of the melody, the idiosyncratic use of vibrato and the presence of non-equal-tempered intervals. After that, some similarity measures between each pair of pieces have been computed, such as the edit distance (Gascuel 1997), in order to obtain a similarity matrix for the studied corpus. We compared the obtained similarity matrix with a set of manual annotations produced by flamenco experts; those manual annotations included perceptual melodic contour, tonal analysis as well as historical data based on previous well-established facts and tenets about the analyzed corpus. The different analyses are presented in the paper, and we will listen to some examples of the analyzed pieces in the conference presentation. Conclusions. Melody is one of the most important aspects to consider when analyzing a cappella flamenco singing styles. Automatic melodic description tools have proven useful to the analysis of flamenco voices, notwithstanding the traditional techniques of music analysis. These automatic tools allow us obtaining quantitative measures that can complement historical data on the roots and the evolution of oral transmission styles. Introduction A cappella singing styles (called cantes or palos in the flamenco jargon) are among the main styles within the flamenco repertoire. Until very recently, flamenco singers have been only using oral transmission to learn them. In oral transmission, melody has become one of the main musical facets to be listened to, remembered, elaborated and spread in flamenco singing styles. Moreover, melody has helped flamenco enthusiasts to remember and identify variants of a particular style or genre. A frequent discussion and also unanswered question among flamenco scholars is how to quantify the similarity between two melodies, and how to use this similarity measure to differentiate different styles and variants among performers, and to study the roots and the evolution of flamenco styles. After some previous studies on rhythmic similarity of flamenco styles (Díaz-Bañez et alt. 2004), we intended to compare complementary approaches for the melodic and tonal analysis of flamenco a capella singing styles. The aim of this work is then to analyze flamenco singing melodies from different perspectives, and use such analyses to compare different versions of the same style. This would eventually lead to a clarification of the roots of styles and their evolution. We provided some historical information, manual melodic and tonal analysis and automatic melodic description tools for the analysis of a corpus of cantes. We carried out a clustering analysis based on similarity measures both for manual and automatic descriptions. In order to achieve this goal, it is also necessary to gather a representative musical corpus, a significantly difficult task due to the variety of media (mostly vinyl and magnetic tapes) and poor quality of existing flamenco recordings. A cappella flamenco Cantes We consider a music collection made of songs without instrumentation or in some cases with some percussion, known in flamenco music as cantes a palo seco. This corpus is composed of tonás. Tonás are songs without any musical accompaniment that in a generic form encompass martinetes, deblas, saetas, tonás and carceleras. In this paper, we concentrate ourselves on two main styles, namely deblas and martinetes. A toná is a song with a ‘copla’ of verses of either three or four or eight syllables, where the second and the forth verses may have assonant rhythm, which is usually finished with an imperfect tercet (off-rhyme tercet). Although its origin is uncertain, many people in the flamenco world believe that the toná is the mother of all flamenco styles (cante madre), and that from it all other styles are derived. Some researchers, honestly trying to build a corpus of research but not counting on a fully rigorous methodology, have dated its origin in the XVIII century in Jerez and Triana CIM08 - Conference on Interdisciplinary Musicology - Proceedings (Molina and Mairena 1963), but more recent studies propose a later appearance (Jaramillo 2002, among others). Many tonás have been given a particular name along history, especially due to the work of Molina and Mairena. Many of those names are merely names familiar to the singers, but they don’t reflect any musical feature. In spite of this fact, they speak about the toná del Cristo, toná de los pajaritos, toná liviana de Tia Sarvaora, toná de la Junquera, toná de Jaunelo, etc. The debla is a song that stems from the basis of the toná. Its melody requires a melismatic ornamentation, more abrupt than the rest of the songs of the tonás group. The martinete is also considered a variety of the toná. It differs from the latter in lyrics and its melodic model, which always finishes in the major mode. It is usually a sad style and it is played without guitar accompaniment, as the tonás group. Nevertheless, martinetes are usually accompanied by the percussion of a mallet struck against an anvil. Singer Antonio Mairena Chano Lobato Chocolate Year 1960 J. Almadén 1985 Jesús Heredia M. Simón 2002 M. Vargas 1972 Naranjito 2002 Pepe de Lucía Talegón 1963 2002 Córdoba Tomás Pabón 1950 Turronero 1989 Triana (Sevilla) Utrera 2002 1999 1985 Location Mairena del Alcor Cádiz Jerez de la Frontera Ciudad Real Écija School Pabón Pabón Mairena Pabón Mairena Pabón Mairena Pabón Mairena Pabón Jerez de la Frontera Cazalla de Mairena la Sierra Triana Pabón (Sevilla) Mairena Algeciras Pabón Music collection Pabón Mairena El Baboso Pabón Mairena Table 1. Set of analyzed pieces. One of the main contributions of this work is to gather a representative music collection for this study. The corpus was found on very diverse media (mostly vinyl and magnetic tapes) and comprises recording from the 40’s up to day. In total, there are 135 monophonic voice pieces covering the most representative flamenco singers. Musicological, geographical and historical criteria were followed when selecting the pieces. For instance, the singer Tomás Pabón is known as the one who established the debla style, and some relevant contributors were Antonio Mairena and Naranjito de Triana. These last two artists are considered as the big masters from the 80’s, and they influenced all the rest of singers. Table 1 provides some details on this music collection. Singer Antonio Mairena Chano Lobato Chocolate J. Almadén J. Heredia M. Simón M. Vargas Naranjito Pepe de Lucía Talegón Tomás Pabón Turronero Key C Major Bb Major G Major B Major Bb Major C Major A Major C Major C# Major C# Major Bb Major B Major Table 2. Keys of the analyzed Deblas. martinete and debla exhibit. From these 135 excerpts, we have started by selecting 12 singers with the most representative deblas and martinetes. The chosen pieces have been manually segmented into phrases, and we have selected the first phrase, as it provides the main melodic theme. This choice has been motivated by the rigidity of musical form that Tonal analysis 3 CIM08 - Conference on Interdisciplinary Musicology - Proceedings 12 10 10 8 6 8 4 2 6 0 4 -2 2 -4 0 -6 Figure 1-a. Manual transcription of a debla performed by Antonio Mairena. Figure 2-a. Manual transcription of a martinete performed by Antonio Mairena. 12 10 8 6 4 2 0 -2 -4 -6 10 8 6 4 2 0 Figure 2-b. Manual transcription of a martinete performed by Tomás Pabón. Figure 1-b. Manual transcription of a debla performed by Tomás Pabón. and Naranjito follow Mairena’s version (in C Major)? A tonal analysis of the selected 12 deblas in terms of global key and modulations is provided in this section. The analyzed deblas provides a modal context, according to the following tonal structure: Tonic (I) Subdominant (IV) - Tonic (I). We observe a wide range of keys at the analyzed pieces, as shown in Table 2. Manual melodic transcription and clustering A manual melodic analysis of our initial corpus was made by a flamenco expert (with formal musical training also). According to its key, we identify 6 different groups: pieces in G Major (Chocolate), A Major (Vargas), Bb Major (Pabón, Lobato and Heredia), B Major (Almadén and Turronero), C Major (Mairena, Simón and Naranjito) and C# Major (Pepe de Lucía and Talegón). For this manual analysis we have first normalized the melodic contour with respect to the tonic, and notes have been approximated to the closest note in the equal-tempered scale. Then, ornamentations or melisma have been removed according to some previous knowledge of the particular style under analysis. We also observe the presence of microtonality in the modulations; most of the times this is due to tuning problems. In fact, the flamenco singer is not trained to perform accurate modulations whatsoever, at least in traditional flamenco singing. There is no straight rhythmic representation, as manual annotation has been made following perception of rhythmic pulses, and not according to note durations. The key is mostly related to the particular tessitura of the singer, but we might wonder if the chosen key could be also related to a similarity between singing styles. For instance, did Lobato and Heredia follow Pabón’s version (in Bb Major)? Or did Simón Figures 1-a and 1-b show graphical representations of the main melodic contour of a debla performed by Antonio Mairena and Tomás Pabón respectively. The reader may observe that there are short-time differences, although the overall melodic contour is similar. 4 CIM08 - Conference on Interdisciplinary Musicology - Proceedings Figures 2-a and b show graphical representations of the main melodic contour of a martinete sung by Antonio Mairena and Tomás Pabón, respectively. We also found some short-time differences, although the overall melodic contour is kept. Computational analysis A computational analysis is made in order to automate the melodic transcription and use alternative similarity distances proposed in the literature. With these manual patterns we have performed a similarity study based on multidimensional scaling, by using the Euclidean distance between the vector representations of the sequential values of melodies. A twodimensional projection of the d-dimensional data is presented in Figure 3. We observe that martinetes (M) and deblas (D) are located in different regions of the 2-D plot. Note that martinetes from Mairena and Pabón (Tomás) are close to each other, whereas their deblas are very far away from each other. State of the art techniques in automatic melodic analysis of audio allow us to obtain different representation levels of a music recording (Gómez et alt. 2003). There are different representation levels for melody. Energy (intensity) and fundamental frequency (pitch) curves are the main low-level melodic features. In a higher structural level, note duration and pitch provide a symbolic representation, which can be the input to higher-level analyses. Finally, deviations of the analyzed recording with respect to the obtained score are related to expressivity. There have been some attempts to apply these techniques to the analysis of flamenco music (Donnier 1997, Gómez and Bonada 2008). 5 CIM08 - Conference on Interdisciplinary Musicology - Proceedings 70 66 68 64 66 62 64 60 62 58 60 56 58 54 56 52 54 0 5 10 15 20 25 note index 30 35 40 45 50 50 0 5 10 15 20 25 note index Figure 4-a. Automatic transcription of a debla performed by Antonio Mairena. Figure 5-a. Automatic transcription of a martinete performed by Antonio Mairena. 70 66 68 64 66 62 64 60 62 58 60 56 58 54 56 52 54 50 0 5 10 15 20 25 note index 30 35 40 45 0 Figure 4-b. Automatic transcription of a debla performed by Tomás Pabón. 5 10 15 note index 20 25 30 Figure 5-b. Automatic transcription of a martinete performed by Tomás Pabón. Figures 4-a and 4-b provide a graphical representations of the extracted melodic contour of a debla performed by Antonio Mairena and Tomás Pabón respectively. We observed some differences with respect to manual annotations. Although there are some errors in the automatic transcription due to the lack of tuning, most of the differences are due to simplifications and assumptions made when manually labeling the melodies (i.e. melisma are not considered, note durations are neglected and only the main melodic anchor points are notated). Automatic melodic transcription We have tested two methods for automatic melodic analysis (Gómez and Bonada 2008, Leman et alt. 2003), which allow us to obtain a MIDI-like representation of singing melodies (onsets, offsets and frequency of every pitch event). It’s important to note that each singer has its own reference tone in mind and he/she sings each note relatively to the scale constructed on that tone (Haus and Pollastri, 2001). It is then necessary to estimate this tuning frequency by dividing the semitone into ten overlapping bins, each one being 0.2 semitones wide with an overlapping region of 0.1 semitones. The mean of the deviations that belong to the maximum bin is the constant average distance in semitones from the user's reference tone. Thus, the scale can be shifted by this estimated amount. Once we had every piece converted into MIDI notes, we needed to normalize it with respect to the key, so that the melodic representation is invariant to transposition. In order to obtain this, we compute the intervals between consecutive pitches, instead of working with the absolute pitch values. 6 CIM08 - Conference on Interdisciplinary Musicology - Proceedings Figure 5. A SplitTree for 12 Deblas and 12 Martinetes. Besides, we wanted the representation of the pieces not to be affected by tempo. We then normalized note durations with respect to the duration of the previous note. The first one is the correlation coefficient between note histograms. We measured how interval distributions correlate without considering its ordering. Correlation indicates the strength and direction of a linear relationship between two random variables. We obtained this coefficient for each pair of pieces, resulting in a similarity matrix. Measures for similarity computation There is a vast corpus of research on how to measure similarity between melodies using computational models, usually inspired in methods for string comparison (Crawford et alt. 1998, Mongeau and Sankoff 1990). The second measure considered was the distance between the note sequences: the edit distance (Mongeau and Sankoff 1990). It is a metric that counts the difference between two sequences under certain operations. The edit distance between two strings is given by the minimum number of operations needed to transform one string into the other, where an operation is an insertion, deletion, or substitution of a single note. Both pitch and note duration information were considered in We implemented several melodic similarity measures. As a preliminary study, we have computed some of them so far to find out which measure would be the most appropriated for our study. For the time being, we have dealt with two different measures. 7 CIM08 - Conference on Interdisciplinary Musicology - Proceedings the algorithm, as they increases the discrimination (López and Rocamora 2005). Díaz-Báñez J. M., G. Farigu, F. Gómez, D. Rappaport, G. T. Toussaint (2004). El Compás Flamenco: A Phylogenetic Analysis. Proceedings of BRIDGES: Mathematical Connections in Art, Music, and Science, Winfield, Kansas, pages 61-70. Phylogenetic trees In addition to similarity analysis, a phylogenetic analysis is made in order to study relationships among the transcribed performances. Donnier, P (1997). Flamenco: elementos para la transcripción del cante y la guitarra. III Congress of the Spanish Ethnomusicology Society. Several techniques exist for generating phylogenetic trees from distance matrices. Once we computed the different similarity matrixes, we generated a phylogenetic tree using the tool SplitsTree (Huson 1998). SplitsTree computes a tree with the property that the distance in the drawing between any two nodes reflects as closely as possible the true distance between the corresponding two pieces in the distance matrix. In Figure 5 we can see a SplitsTree generated with the similarity matrix between note histograms. As expected, due to the different melodic contour of every style, two clusters appeared: a first cluster with the deblas, and a second clearly distinct cluster including the martinetes. Dress, A., Huson, D. and Moulton, V. (1996). Analysing and visualizing sequence and distance data using SPLITSTREE. Discrete Applied Mathematics, 71:95-109. Gascuel, O. (1997), “BIONJ: an improved version of the NJ algorithm based on a simple model of sequence data,” Molecular Biology and Evolution, 14, pp. 685-695. Gómez, E. Klapuri, A. Meudic, B. (2003). Melody Description and Extraction in the Context of Music Content Processing, Journal of New Music Research Vol.32 .1, 2003. Conclusions and future work Gómez, E. and Bonada, J. (2008). Automatic Melodic Transcription of Flamenco Singing, Conference on Interdisciplinary Musicology, 2008, Thessaloniki, Greece. Melody is one of the most important aspects to be considered in the analysis of a cappella flamenco singing styles. Automatic melodic description tools can be effectively used to the analysis of flamenco singing. These automatic tools allow obtaining quantitative and qualitative measures that can complement historical and musical data (and other types) on the roots and evolution of oral transmission of flamenco styles. Hernández Jaramillo, J. M. (2002). La Música Preflamenca, Sevilla, Consejería de Relaciones Institucionales - Junta de Andalucía. Haus, G. and Pollastri, E. (2001). An Audio Front End for Query-by-Humming Systems. In Proc. of ISMIR 2001, Bloomington, IN, Usa, Oct. Acknowledgments. This work is partially funded by Agencia Andaluza para el Desarrollo del Flamenco, Spain through the COFLA project: Computational analysis of flamenco music. Huson, D. H. (1998). SplitsTree: Analyzing and visualizing evolutionary data, Bioinformatics, 14:68-73. Lerman, M., Martens, J. P. , De Baets, B. De Meyer, H. MAMI. Versión 2.0, 2003. University of Ghent, http://www.ipem.ugent.be/MAMI. References T. Crawford, C.S. Iliopoulos, R. Raman (1998), String matching techniques for musical similarity and melodic recognition, Computing in Musicology. 8 CIM08 - Conference on Interdisciplinary Musicology - Proceedings López, E., Rocamora, M. (2005) Tararira: Sistema de búsqueda de música por melodía cantada, 10th Brazilian Symposium on Computer Music, http://iie.fing.edu.uy/investigacion/grupos/gmm/p royectos/tararira/index Molina, R., Mairena, A. (1963). Mundo y formas del cante flamenco, Ed. Revista de Occidente, Madrid, 1963. Mongeau, M., Sankoff, D. (1990), Comparison of musical sequences, Computers and the Humanities, 24:161–175. 9