[continued]
While this section is introductory in character, the first four measures serve in fact to define Texture I, which closely resembles the envelope characteristics of a gong sound: attack (tenor drum and bass drums); steady state (gong and tam-tams); growth and decay (sirens, snare drum without snare, and cymbals). Elements from this texture are seldom absent throughout the piece. Thus, Texture I may be regarded as the foundation in Ionisation's structure, a kind of textural “pedal,” with metal serving as the timbral “center” of the whole piece. Germinal rhythmic ideas in the subsequent measures of this section anticipate later development.
While the parade-drum passage, in a “classical” guise of 2+2 measures, appears to take on the character of a “theme,” it is no more than a succession of typical snare-drum stick techniques. The definition of Texture II largely depends on the other instruments carefully “orchestrated” in terms of timbre and register: bongos/maracas in higher register, deep bass drum/hand cymbals in a lower one, with the first phrase marked off by slap-stick/tenor drum and the second by string drum/deep bass drum.
The close relationship of the three textures of Ionisation is revealed after measure 13, where in quick succession Texture I and II lead on to Texture III, at measure 18. The wood-blocks passage suggests a combination of the parade-drum and bongo motives, “modulated” to by way of tarole in rhythm, timbre, and register. The wood blocks/tarole sonority is complemented by a “rattle” sonority (sleigh bells/castanets/tambourine). Thus, Texture III is assigned to the highest of the three textural registers.
Section 4 begins a linear elaboration of Texture II in juxtaposition with Texture III. Many diluted sonorities from Texture I are also present (especially after measure 25). The presence of bass drums is however a different matter. It represents a timbral transformation of the instruments (now with wooden sticks) and a change in register of the bongo motive, partly to accommodate Texture III (the parade drum’s register also being lowered by the use of felt sticks) and partly to allow bongos to exchange material with parade drum.