Our story
We are Johannes Härle and Johannes Kotte. We share the conviction that acoustics needs to be rethought. Out of this conviction grew our shared vision: to develop sustainable acoustic solutions and establish a new industry standard.
1970s/80sThe beginning of an idea
In the 1970s and 1980s, Hans A. Härle, the father of Johannes Härle, developed a sintered-metal soot particulate filter. While its original purpose was to reduce emissions, it revealed an unexpected side effect: the open-pored metal structure absorbed engine noise so effectively that acoustic engineers later had to amplify the engine sound artificially. From this discovery came the idea of using metal deliberately for acoustic applications.
1980s–2000sDecades of development
Guided by the principle “lighter, better, cheaper”, Hans Härle developed numerous solutions for companies such as Mercedes-Benz, Audi, Volkswagen, ZF and STIHL. His work led to more than 150 patents, all of which were successfully brought into series production. For this exceptional record of innovation he received, among other honours, the Rudolf Diesel Medal.
1995-2010An industry at a standstill
Micro-perforated absorbers offered outstanding acoustic properties but were expensive to manufacture and hard to automate. Many European manufacturers ceased production or switched to conventional sandwich materials. A promising technology was in danger of disappearing from everyday industrial use.
From 2013A fresh start
In 2013, Hans A. Härle and Johannes K. Härle began developing a new generation of micro-structured metals. The goal was a material that is more capable, more robust and more economical — and, for the first time, efficient to produce in large quantities.
2018–2022Refinement
After Hans Härle's death in 2018, Johannes K. Härle continued the development together with Johannes Kotte. New manufacturing processes and innovative geometries opened up possibilities previously considered unfeasible. The result is Absora-sheet (Härle Sound Absorber, 3rd generation) — a multifunctional metamaterial that combines sound absorption, high stiffness, lightweight construction and automated manufacturing. Thanks to its special geometry, Absora-sheet achieves an exceptionally broadband acoustic effect and opens up entirely new applications in industry, mobility and construction.
2023–2024The founding of ABSORA
In 2023, Johannes K. Härle and Johannes Kotte founded ABSORA GmbH. The vision: to establish Absora-sheet as a new industry standard and to bring sustainable, fully automated manufacturing back to Europe. The focus is on resource efficiency, recyclability and new applications that reduce material, weight and CO₂ emissions.
TodayThe next step
With a growing patent portfolio, a successful pre-seed round and strong industry partnerships, ABSORA is preparing its next step: the industrial series production of Absora-sheet and the build-up of a platform for the next generation of sustainable acoustic and lightweight solutions.