ZIKADEN



Zikaden installation was introduced by Tonoptik in August 2016 in Saint-Petersburg. Built into the city park it is an experimental audio-visual composition generated in real-time with source of more than thirty device units. These devices operate according to certain algorithms, with some probability defining the nature of sound and its role in the overall rhythmic structure. Built-in LEDs generate light pulses repeating sound intervals, thus accompanying its generation in details.

All devices are divided into three groups, and each of these groups has its allowable band of quantitative sound characteristics and specific set of input data for the algorithm, which describes the rhythmic pattern at the current time interval. Together they form a polyrhythmic structure complicated by random input data variable over time. This structure is distorted under the influence of physical factors affecting the continued operation of microcontrollers.


The basic rhythmic pattern of the installation makes up the Euclidean rhythms. To generate rhythms, an Bjorklund algorithm is used. Initially this algorithm was designed to solve the problem considered by Bjorklund in connection with the operation of certain components of Spallation Neutron Source (SNS) accelerators used in nuclear physics. Time is divided into intervals and during some of these intervals a gate is to be enabled by a timing system that generates pulses that accomplish this task.

This algorithm corresponds to one of the oldest known algorithms described in the "elements" of Euclid. Today it is called the Euclidean algorithm for finding the greatest common divisor of two given integers. If these two numbers are equal respectively to the number of ones and zeros in a binary sequence, then the structure of the Euclidean algorithm is the same as the structure of the Bjorklund algorithm.

Such binary sequences may be represented as a family of rhythms called Euclidean due to relations of structures of these elements. Thus, the algorithm above allows to generate rhythms in a wide variety of styles, ranging from the Persian rhythms of the thirteenth century to the Afro-Cuban pieces for percussion or rhythms that are inherent in many modern performers.

To animate the generated composition and to vary, following the experiments of the musician and architect Yanis Xenakis, used stochastic function. Xenakis referred as an example to natural phenomena such as the sound of the knocking of the rain on the roof or the singing of cicadas. Sound effects, considered as a whole, but composed of dozens of individual sounds. These sounds together form a flexible holistic phenomenon, transforming in time.

Each sound can be decomposed into: duration, frequency, interval, and number of pulses. And each such component is defined by using probabilistic algorithms. At the same time, the used microcontrollers allow to generate random numbers caused by the analogue noise transmitted to one of the inputs. In contrast to the generation of pseudo-random values that guarantees a non-repeatable sequence of received values (unless such repetition is not an accident).


Considering the fact that each device works independently of the others, the overall composition at different periods of time can be almost chaotic or, vice versa, evolved in a graceful rhythmic structure by the action of probabilistic functions. Thus, due to random coincidences generated using the Bjorklund algorithm rhythms sometimes remind of some natural phenomena, intuitively unavailable for exact systematization, but from time to time turning into complexly structured polyrhythmic patterns.