1. Mixing the three percussion instruments
The orchestra’s three percussion instruments work in collaboration to create a single rhythmic pattern that provides the composition with a regular metric outline in support of the melody. It has its own internal hierarchy, where the shôkô functions to articulate the downbeat of every measure, and the kakko’s role is to control the accelerandos that lead to some selected downbeats. The function of the taiko is to articulate the most important downbeat of the entire phrase: its half-point called the obachi. As a matter of fact, obachi is the only beat where the three percussion instruments meet. Example 1 shows the basic rhythmic pattern used in the phrase structure of 4 measures with 4 pulsations per measure. (It must be emphasized that while the obachi is structurally positioned at the cycle's half-point, this is not how the musicians with whom we worked think about it. Rather, some describe it as the marker of the cycle's first measure, while others think of it as a marker of the last measure of the cycle.)
The taiko’s part is easy, with only two attacks per cycle, and it is also difficult because the performer cannot afford loosing count, since one of the two attacks is the cycle’s most important one. Hence the performance of the taiko includes hand gestures that add a ceremonial tone to the performance and also help the performer keep up with counting. After the half-point attack, the player’s left arm makes a circular motion and brings his/her left hand to rest on his/her left thigh, at which point the right arm performs a similar gesture and brings his/her right hand to rest on his/her right thigh. Then the left hand gets in place to perform the mebachi followed by the right hand being ready to perform the obachi, at which point the arm patterns start over again.
Although the three percussion instruments are united in producing a single rhythmic pattern, their different functions and timbres prevent them from merging into a single sonority. As shown in Example 1, the two most active instruments are the shôkô and the kakko. The reason why their superposed sound remain clearly distinguishable is related to the fact that the former is an idiophone and the latter a membranophone, and because their sound occupies two separate areas on the frequency scale as demonstrated in Figure 1, which shows that the energetic pattern of shôkô’s sound (in blue) starts around 3930 Hz, while the kakko’s (in red) is located between 350-1100 Hz.
Comparison between the frequency areas occupied by the sounds of the kakko (in red) and the shôko (in blue)
The different timbre of the percussion instruments helps articulate the phrase structure at three different speed levels. The first level of articulation is the fastest one, and it comes from the high and piercing attack of the shôkô, which usually marks off the downbeat of every measure. The second level of articulation is an intermediate one, and it comes from the kakko, whose roll emphasizes selected downbeats, usually one every two measures. Finally, the last level of articulation is the slowest one, and it comes from the taiko's obachi, which accentuates the most important downbeat of the entire cycle: its mid-point.
As demonstrated in the other chapters under 'Orchestration', timbral transformations and phrase structure go hand-in-hand. The macro rhythm created by the percussion instruments provides the listener with a temporal canvas against which one can appreciate the transformations of timbre in the other sections.