First Pan-American/Iberian Meeting on Acoustics, Cancun, 2-6 December, 2002.
Ancient Noise Generators
Roberto Velázquez (email@example.com)
Sergio Beristain (firstname.lastname@example.org)
Rolando Menchaca (email@example.com)
Instituto Politécnico Nacional
In Ancient Mexico, there has been found a whole family of artifacts, which produce singing noises. The original purpose of these artifacts is unknown, but some scholars think that some were used in mortuary ceremonies and employed by H-men and other can produce very special sounds like those of animals from the jungle, wind or the underworld.
The simplest Mexica (Aztec) noise generator appears in the Florentine Codex, in the upper left corner of Figure 1. It was recognized by Guillermo Contreras . Jorge Dájer included in his book  the picture of a Purepecha bone aerophone (Figure 2). It is very similar to the aerophone of Florentine Codex.
Until last century very similar mouth whistles were (Figure 3) used as toys in rural towns. It was analyzed in a previous study . Similar whistles were used in several zones of the world .
Other member of this noisy family is the Olmecan whistle (Figure 4), previously analyzed [5, 6 & 7]. Nearly 4.5 tons (140,000 pieces) of multi-drilled little black stones were found at San Lorenzo , but their sonic property was not known. Figure 5 shows their cross-section views drawings. The previous mouth whistles are played inside the mouth (Figure 6).
Ancient noise generators have been called "of spring or diaphragm of air" or "whistles of the death". Jose Luis Franco studied some of them and other more complex  because they are played outside the mouth, but with similar sounding mechanism. Susan Rawcliffe examined and reproduced many similar "complex flute systems" . One of them was the Olmecan Gamitadera (Figure 7) that was studies previously [11 & 12]. His designation is related with the "Gamito" (deer). For the hunters, "gamitear" means to produce the sound of the little animal to attract the adult male of female to hunt them.
Some Mexican artisans of the singer clay (Mario and Gregorio Cortes) and musicians (Group Tribu) make some replicas of these noisy aerophones and several hundreds of experimental models were made and analyzed.
They can produce sounds with wide band frequency spectrums and some time very clear tones are identify. Small changes in the structure and dimensions of their sounding mechanism can affect the frequency components (timber, loudness, band, etc.) and the sound produced (Figure 8).
The radiated acoustic power of some experimental replicas are impressive (0.3 Watts) and more loud if they are coupled with a simple resonating tube like a clay or gourd trumpet (Figure 9). Figure 10 shows its spectrogram with wide band noise, but powerful crests due to the resonating tube.
The effects of these noisy whistles are unknown, but if they are played in big groups some very special effects could be produced, because their chorus can generate random infrasonic beats.
Some acoustic models where proposed to explain their general behavior, using in analogies of electric circuits [11 & 12], but the detailed dynamics of the production system of sounds of this type of aerophones is not known. From the mathematical point of view, it seems that this system belongs to the field of the models of stochastic-not-linear-dynamic systems, since they operate in an wide range of vibrations, pressures and non periodic waves of sound, within three very small chambers and two special circular edges, like a chaotic and turbulent process. This class of mathematical models is in the border of several advanced fields of the science, like the generation of complex sounds, the dynamics of vortex, dynamic of turbulent flows and scientific visualization. But, it was not possible to find institutions, laboratories, equipment and personnel suitable and available to develop their formal investigation, and the ancient aerophones stored in museums were not available for independent researches.
1. Contreras-Arias, Juan Guillermo, 1988, "Atlas Cultural de México. México", SEP, INAH, Grupo Editorial Planeta.
2. Dájer, Jorge. "Los artefactos Sonoros Precolombinos, Desde su Descubrimiento en Michoacán", FONCA-ELA. México. 1995.
3. Velázquez-Cabrera Roberto. "My first whistle". (http://geocities.com/rvelaz.geo/corcho/cup.html)
4. Armengaud, Cristine, "Musique Vertes", 3. Ed. Cristine Bonneton Editeur, 1984. ISBN 2-862353-044-1.
5. Velázquez-Cabrera, Roberto. "Black Stone Aerophone". Conference for the Computing International Congress CIC-2000, Instituto Politécnico Nacional, México, D. F., on November 16, 2000. (http://www.geocities.com/rvelaz.geo/bstone/bstone.html)
6. Velázquez-Cabrera, Roberto. A magical aerophone from the olmec infraworld?. (http://www.geocities.com/rvelaz.geo/bstone/smagici.html)
7. Velázquez-Cabrera, Roberto, Beristain, Sergio and Menchaca, Rolando. "Acoustical analysis of an olmecan whistle", 143rd Meeting of the Acoustical Society of America, Pittsburgh, Pennsylvania, June 2 - 7, 2002.
8. Cyphers, Ann and di Castro, Anna, "Los artefactos multiperforados de ilmenite en San Lorenzo", Arqueología, Revista de la Coordinación Nacional de Arqueología del INAH/Segunda época, 16, Julio-diciembre 1996.
9. Franco, Jose Luis. "Musical Instruments from Central Veracruz in Classic Times", Ancient Art of Veracruz, Exhibition Catalog of the Los Angeles County Museum of Narural History, 1971.
10. Rawcliffe, Susan, 1986, "Complex Acoustics in Pre-Columbian Flute Systems", Experimental Musical Instruments, Organology, Vol. III, #2, Published in the book "Musical Repercussions of 1942.
11. Velázquez-Cabrera, Roberto. "Virtual Analysis of Gamitadera", Conference for the 7º. Mexican Congress of Acoustics, Veracruz, Ver. Mexico, October 27, 2000. (http://www.geocities.com/rvelaz.geo/gamitoi/gamito.html")
12. Menchaca-Garcia F. Rolando y Velázquez-Cabrera, Roberto, 2000, "Análisis Acústico de Artefactos Sonoros de Viento del Mé;xico Antiguo". Conference for the 7º. Mexican Congress on Acoustics, celebrated in Veracruz City, México, october 26 and 27, 2000.
Fig. 1. Florentine Codex. Mixcoacalli Instruments. Lam. 70
Fig. 2. Ocarina from Araró (Dajer´s Picture)
Fig. 3 A "corcholata" (metallic cup for soda and beer bottles) whistle.
Fig. 4. Olmecan whistle or multi-drilled black stone
Fig. 5. Drawings of the cross sections
Fig. 6. Way of playing the multi-drilled stone
Fig. 7. The Gamitadera
Fig. 8. Spectrograms of Gamitadera models.
Fig 9. Noisy whistle and a trumpet of gourd
Fig. 10. Spectrograma of the sound from the noisy trumpet