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 developed the sintered-metal soot particulate filter that is found today in millions of cars and trucks. Its original purpose was to reduce emissions – first so that truck races in Mexico could be broadcast on TV, then in California for ecological reasons. An unexpected side effect emerged: 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. The first products to come out of this were so-called liners for the aviation industry.
1980s–2000sDecades of experience
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, every one of which was successfully brought into series production. This was down to his focus on innovative production processes. For this exceptional record of economic innovation he received, among other honours, the Rudolf Diesel Medal awarded on the 150th anniversary – alongside Enercon’s founder, SAP and ebm-papst.
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.