Martin Breindl/Bernhard Kathan, HZWEIO
a generative ecological sound installation, 2015/2022
6 mash barrels, approx. 600 used PET bottles, 6 microphones, mixer, amplifier, 4 loudspeakers

installation view Viertelfestival Hollabrunn, A, 2022; photo by KseniaYurkova

HZWEIO is a generative sound installation. Six mash barrels with a capacity of about two hundred litres each, either black or dark blue, are mounted on an outside wall, facing south, exposed to direct sunlight. Each of the barrels contains about one hundred empty PET bottles which are slightly pinched and hermetically sealed again. The plastic bottles expand with increasing temperature and contract when the environment cools down. Expansion as well as contraction produce a variety of click and plop noises on a low volume. High quality capacitor microphones pick up these sounds from within the barrels, transmit them to a mixing desk where they are filtered and amplified. This live feed distinctively is heard from a four-channel loudspeaker system, which is arranged in public space.

The sounds neither are electronically treated nor manipulated. Nevertheless they produce an irritation of the normal acoustic environment in adding strange and normally unheard sonic events to the everyday soundscape. As the installation is operated by simple laws of physics – expansion of air by increase / compression by decrease of temperature – the density of the sound events increases at daybreak, when sun is warming up the barrels, then becomes almost mute at noon, and accelerate again at sunset, when the air cools down rapidly. It follows an algorithm entirely bound to the laws of nature, of a rhythm of day and night as well as of changes of temperature due to weather conditions.

Although the installation neither uses water itself nor its sounds, it gives way to a variety of associations connected with the topic of water. Plastic barrels and PET bottles are containers of water if water is not available as a natural resource. Even though they are useful they are at the same time a severe threat to the ecological system of the oceans, currents and lakes of the whole earth. The fact that water itself is becoming a scarce resource in the wake of the climate catastrophe has become clearly visible in recent years as dehydration of the soil. And that's why the ideal place for the installation is exactly in such places, as an acoustic warning signal that the water balance has already changed.

The prototype of HZWEIO was set up in 2015 in the HIDDEN MUSEUM in Fraxern, A. The installation was shortlisted for the Tesla-Award 2018 and finally realised in 2022 in two different versions at the minus20degree festival in Flachau, Sbg., and at the Viertelfestival in Hollabrunn, Lower Austria.
Video, 03:26, by Ksenia Yurkova

___ Hollabrunn, A, municipal water reservoir Alte Hofmühle, 21.5. – 14.8.2022, Viertelfestival NÖ
___ Flachau, A, Kirchplatz, 20. – 23.1.2022, festival minus20degree
___ HIDDEN MUSEUM, Fraxern, A, 1. – 31.7.2015

___ Bernhard Kathan, H Z W E I O, 2022
___ Bernhard Kathan, Musikalische Kühe und die Klangmaschine (Musical cows and the sound machine), 2015 [German only]

drawing by Martin Breindl

Set up:

– 6 mash barrels, blue, 200 l

– about 600 used PET bottles


– 2 mics AKG 430

– 2 mics Sennheiser E 901

– 2 mics Shure Beta-91-A

– 1 mixer, 6 in/ 4 out, FX

– 2 stereo amplifiers

– 4 speakers, weatherproof

– Microphone and speaker cables