ON SOME PARALLELS BETWEEN THE VOCAL APPARATUS AND MUSICAL INSTRUMENTS, AND THEIR CONSEQUENCES FOR THE EVOLUTION OF LANGUAGE AND MUSIC

摘要

In this paper we argue that (1) the vocal apparatus and musical instruments are both source-filter devices; (2) the way these devices work help us understand what phonological and melodic sound systems share and what they don't; (3) this comparative approach can shed light on the evolution of language and music. The Source-Filter Theory (Fant, 1960), asserts that the speech sounds result from two consecutive processes: a source produces an initial sound and a filter modifies it. Basically, when a human speaks the vibration of the vocal cords function as a glottal source of energy and the displacement of the organs of the mouth and throat function as the filter. The combined action of source and filter produces the two phonological macro-categories, consonants and vowels. With this mechanism, a human can produce thousands of syllables, which are the basic building blocks of speech. The English syllables inventory, for example, runs to something around 16,000 syllables (Barker, s.d.). Musical instruments can be seen as source-filter devices as well. The source-function can be performed by the strings of a guitar, the wooden bars of a xylophone, the reed of a clarinet, and so on, while the filter-function is performed by sound boxes and tubes in many different shapes and sizes, built from a whole array of different materials. However, musical instruments present a crucial difference in relation to the vocal apparatus: their filters are permanently static. One can pluck or bow the strings of a violin but one cannot change the shape of its body. This is true for any melodic instrument, even for those which apparently have a movable filter, like the jew's harp or the trombone, for example. As tones are the outcome of the source vibration, we have nothing but tones as the output of a musical instrument. In this order of ideas, the mobility of the filter seems to be the key factor distinguishing musical and linguistic sounds, which are therefore organized in systems conversely oriented.