Clay singer birds
Roberto Velázquez Cabrera
Virtual Research Institute Tlapitzcalzin
First version, April 24, 2003.
(Versión en Español)
Clay birds are one of the best type of ancient aerophones, because they represent the taste, veneration and philosophy of ancient people, related with their sacred beings from nature and their beautiful music. Those aerophones can produce sounds similar to those of natural birds. Their best characteristic is the posibility to generate microtonal (micropitch) sounds, free intonation or continuos changes of pitch under a wide band of frequencies.
Their main organological element is the big size of their tone holes (up to 2 or 3 cm of diameter) to be able to change the pitch and the open/close modes in a continuos way. They can have one of several resonating chambers to produce complex sounds like beats in a wide range of continuos pitch. The sounds can be very complex if the blowing, fingers, lips and tonge are operated in a complex way.
The sounding mechanism (air way, mouth and edge) and the resonator must be almost perfect, to be able to produce loud and clear sounds.
The tone holes can be from one to four and be located at their back (the bigest), at the front of the aerophones, at their sides and at any other place. The pitch holes can be not only circular, but almost of any whised shape. They can be operated with the fingers af one hand and the lips.
The external shape of the body may be the head of a bird or of another animals. The size of the resonaring chamber and pitch holes dimensions determine the main tesiture.
One interesting feachure of many ancient clay aerophones is that their tesiture is in the range of the maximun hearing sensitibity of human beings and birds (1-5 KHz) due to the small size of their resonating chambers.
The range of the continuos pitch variation, can be up to an octave. They can produce many flat musical notes and they operate like a Helmholtz's resonator, when they play single flat musical sounds, but their dynamic mathematical model is unknown when they are played in a complex way. Their most complex sounds are very difficult to be written in a realistic way, like those of natural birds.
For example, This is a simple wav sound and its spectrogram, with a increased pitch from 1170 Hz to 2444 Hz, a bandwidth of more that 1200 Hz or nearly an octave. The signal has several harmonics and it is loud. This is the wav sound of a clay bird and its spectrogram has complex frequency components with a fundamental (F0) that seems waves.
It is possible "to talk" with natural singer birds with those kind of sounds and the most beautiful effect is to produce chorus of birds with a big set of those aerophones made in different sizes and operated in a complex way. They can produce complex beats in several tesitures, when they have several resonating chambers or when a set of aerophones are played at the same time.
Some members of this family of mexican aerophones and their sings were presented in the 1st Special Session on Acoustics of Ancient Musical/Sonorous Instruments/Artifacts as examples of simple aerophones that can produce complex sounds if they are made and operated in an ancient way.