Acoustics of the Flautas de Chinos

In central Chile, a sacred musical ritual dated from pre-hispanic times, has survived centuries of segregation, misunderstanding and alienation, first from the european regard and later from their own mestizo compatriots. The ritual incorporates dance and music produced by bands of flutes whose sound is not conceived under any formal aesthetic paradigm but as an ingredient to stimulate and perturb their senses creating a sort of trance in performers and great excitation in the community. The ritual can last several hours and the sound can reach impressive loudness that can be heard from distances of hundreds of meters. Groups of about 20 musicians split in two teams and armed with flutes of different sizes, repetitively alter sound clusters that fill the space, time and frequency spectrum. The musicians are referred to as “chinos”, a spanish deviation from a Quechua word which means servant. They are serving catholic divinities in a continuously evolving tradition that has adopted the overwhelming influence of christianity in Latin America. An anthropologic and ethnomusicologic study of the ritual is required to properly describe it but, for the moment, is beyond the scope of this article. Throughout the paper acoustical aspects of the instruments are described as well as some observations on the instrumental technique: the simplicity of their construction, materials and geometry, their acoustical impedance, the mechanisms of playing and their characteristic sound called sonido rajado (literally torn sound) are addressed. The complex resonator of the instrument, formed by two wooden cylindrical bore sections of different radius, no toneholes, and one closed end, is described in detail. An analytical model of its impedance is proposed and contrasted with measurements and spectrum analysis of field recorded sounds. Measurements of the control parameters show that the flow needed to produce the sound is about ten times larger than the one used on european transverse flute. High-speed visualizations of the air jet show its turbulent behaviors as well lips oscillations that could relate to the production of the sonido rajado. INTRODUCTION The flutes studied in this article are ritual flutes used by Chilean fraternities called Bailes de Chinos, that are involved in popular Catholic festivities in the central coast of Chile. The quality and manner of the execution of these flutes is inseparable from a set of expressive resources that engage, outside the instrumental sound, movement, choreography and singing. Each Baile is formed by a variable number of performers arranged in two rows of 10 to 24 chinos dressed up in a uniform and ordered decreasingly according to the length of their flutes. From the leading flute, called punteras, measuring about 70 cm down to the smallest flute called coleras of about 30 cm length (de Arce 1998, Wright and Campbell 1998). The Baile is also formed by a bombero, responsible of marking the binary pulse that makes each row of flute players alternate; a drummer who shows the choreography movements (mudanzas) to be followed by the performers; and the alferez with a priestly mediation function through a devotional song and greeting a lo divino (to the divine), organized in quatrains and occasionally in tenths, both octosyllabic. Except from the alferez chant, whose style is related to vernacular-religious music from the Hispano-arabic tradition, the collective performance of these flute rituals does not respond to any western musical reference, so we prefer to characterize it symbolically as an expressive completion power. Both the design and execution of the flautas de Chinos seek to produce a sound that fills, in each breath, the sound spectrum of the instrument. The completion act is achieved in several ways simultaneously: as a cluster of frequencies, as a continuous sound in time domain and as a circular alternation of the two blowing rows where the attacks are marked and dissipated simultaneously. We also note that the completion in acoustics terms, has a counterpart in the symbolic-expressive plane. The movements of the performers are not independent from the instrumental control. They relate to each other through the aerobic demand. The enormous amount of air required to properly blow the flutes produces hyperventilation, which is compensated by extreme physical demands: moving, rotating, and jumping for hours as in the Mapuchean purrun, or as in some dervishes or meditation dances. Moreover, the falling jump coincides with