BOHEME’s ambitious goal is to design and realize a new class of bioinspired mechanical metamaterials for novel applicative tools in diverse technological fields. Metamaterials exhibit exotic vibrational properties currently unavailable in Nature, and numerous important applications are emerging. However, universally valid design criteria are currently lacking, and their effectiveness is presently restricted to limited frequency ranges. BOHEME starts from an innovative assumption, increasingly supported by experimental evidence, that the working principle behind metamaterials is already exploited in Nature, and that through evolution, this has given rise to optimized designs for impact damping. The “fundamental science” part of the project aims to explore biological structural materials for evidence of this, to investigate novel optimized bioinspired designs (e.g. porous hierarchical structures spanning various length scales) using state-of-the-art analytical and numerical approaches, to design and manufacture vibrationally effective structures, and to experimentally verify their performance over wide frequency ranges. The project involves theoretical, numerical and experimental aspects, and is a high-impact endeavour, from which basic science, EU industry and society can benefit.
Contact: Andrea Bergamini
Funding: Horizon 2020
Partner: UNITN, Imperial, IMP-PAN, ETH Zürich, UNITO, Multiwave, Phononic Vibes, POLITO, CNRS
Duration: 2020 - 2023

Optimized high-lift system for low noise approaches, including best configuration for landing (DYNCAT)
DYNCAT aims at enabling more environmentally friendly and more predictable flight profiles in the Terminal Manoeuvring Area TMA, namely on approach, by supporting the pilots in configuration management. Approach and take-off operations at busy airports are virtually always less noise and fuel efficient than possible due very rigid constraints imposed on the flight profiles by Air Traffic Control ATC (concerning both vertical profiles and speed regimes), but also due to lack of support to the pilots for dealing with given restrictions/constraints and actual weather in the optimum way. Current FMS functionalities do not support configuration management very well, only a simplified, static high-lift sequence with a fixed order is available. The adequacy of actual procedure flown depends very much on the pilots' skills, but also on their access to information such as actual wind situation and ATC intents.
The objectives of the project are (a) to analyze the impact of current mismatch of aircraft and ATC procedures on flyability (pilot workload, safety) and environmental impact (fuel burn and CO2; noise), (b) to propose amendments to on-board and ground procedures including identification of necessary enablers (technical, regulatory) and (c) to quantify ecological and economical potential of proposed improvements, including the prediction of 4D Trajectories, through exemplary analysis and early prototype simulation of newly designed configuration management functionality.
The study will be done exemplarily using the A320 family as reference aircraft and the development of new FMS functionalities for the optimization of the high-lift system sequencing during approach as use case. Access to recordings of actual flight operational data, associated ATC instructions issued, weather data and noise measurements for a large number of operations in Swiss airspace on one hand and the implementation of the improved functionalities on an industrial test platform on the other allow for high validity and relevance of the results.
Contact: Christoph Zellmann
Funding: Horizon 2020 (SESAR)
Partner: DLR, Swiss Airlines, THALES, SkyLab
Duration: 2020 - 2022

Shunted electroactive membrane absorbers (SEMA)
Resonating thin membranes in front of an air cavity are efficient sound absorbers. The frequency of maximum absorption depends on the membranes stiffness, pretension, and geometry. Low frequency sound absorption requires large membranes or thick cavities. Tuning membrane low frequency absorbers is not straightforward. If the membrane's strain generates a voltage, the electromechanical coupling can be used to tune its resonance frequency in a different way. A circuit consisting of the capacitive membrane, a resistor and an inductance gives rise to an electrical resonance, at which the membrane's stiffness is significantly reduced. The electrical eigenfrequency can be easily tuned to any frequency, independent of the tension in the membrane. This project investigates practical ways of achieving high sound absorption using this principle.
Contact: Bart Van Damme
Funding: SNSF
Duration: 2020

Comparison of aircraft noise calculation schemes FLULA2, AEDT and sonAIR with measurements
In this project, two large aircraft noise measurement dataset will be compared with model calculations of  FLULA2, AEDT (as conformal implementation of Doc.29 and Doc.9911 respectively) and sonAIR. The focus lies on comparing on LAE, LAE,t10 und LAmax, but additionally also level vs. time pattern will be analyzed.
Contact: Beat Schäffer
Funding: FOEN
Duration: 2020

Multisensory dimensions of forest attractiveness
Current research results provide clear indications that negative effects of noise, both in terms of annoyance and health effects, can be reduced by the presence of green spaces and recreational areas. Particularly in urban areas, the design of public spaces and the maintenance and promotion of local recreational areas can therefore contribute to reducing the negative effects of noise pollution. These forms of noise protection shall be evaluated with regard to their effectiveness and further developed in their implementation in order to meet the conflicting requirements of noise protection and spatial planning. Within the framework of this project, Empa, in collaboration with WSL, will investigate the question of what requirements forests in urban areas must meet in order to fulfil their function as recreational areas, and what defines the quality of forest recreation areas.
Contact: Jean Marc Wunderli
Funding: FOEN
Partner: WSL
Duration: 2020

Prediction of sound insulation in multi-storey solid wooden construction (SPiMM)
The share of timber construction in multi-storey new buildings is also increasing steadily in Switzerland. A detailed sound insulation calculation has not yet been possible. In order to make noise control pre-dictable, calculation processes are reviewed in this first project phase, taking into account the connec-tions between solid wood components: The applicability of the methods required for the calculation and the availability of the necessary input data are investigate exemplarily at a building junction with rigid connetions.
Contact: Stefan Schoenwald
Project funding: BAFU
Duration: 2020

Impact sound insulation of solid wood floors with acoustic black hole (TriMASL)
Use of so-called "acoustic black holes" to improve the impact sound insulation in solid wood floors. This reduces the mass of floor toppings that was previously necessary for sound-insulation, thus further expanding the technical and economic advantages of timber construction. The aim of the investigation is the development of design and optimization methods and the implementation of a technology de-monstrator.
Contact: Stefan Schoenwald
Project funding: BAFU
Duration: 2019 - 2021

Development of a calculation tool for a low-noise operation of multicopters
It is becoming apparent that the use of multicopters will increase strongly in the coming years, not only privately but also commercially. Authorization of commercial use must cover not only flight safety aspects but also noise issues. In the present project, a tool is therefore being developed which provides the necessary basis for this. The tool is based on sonAIR, the existing software for calculating aircraft noise. sonAIR will be expanded to allow the planning of operations of commercially used, electrically operated multicopter aircraft and the calculation of the resulting noise pollution. Furthermore, recommendations for low-noise products and noise-reduced operations will be developed, thus contributing to the reduction of noise pollution.
Contact: Jean Marc Wunderli
Funding: FOCA
Partner: ALR, n-Sphere, Meteomatics, Matternet
Duration: 2019 - 2020

Localization and Identification Of moving Noise sources (LION)
Sound source localisation methods are widely used in the automotive, railway, and aircraft industries. Many different methods are available for the analysis of sound sources at rest. However, methods for the analysis of moving sound sources still suffer from the complexities introduced by the Doppler frequency shift, the relatively short measuring times, and propagation effects in the atmosphere. The project LION combines the expertise of four research groups from three countries working in the field of sound source localisation: The Beuth Hochschule für Technik Berlin (Beuth), the Turbomachineryand Thermoacoustics chair at TU-Berlin (TUB), the Acoustic Research Institute (ARI) of the Austrian Academy of Sciences in Vienna and the Swiss laboratory for Acoustics / Noise Control of EMPA. The mentioned institutions cooperate to improve and extend the existing methods for the analysis of moving sound sources. They want to increase the dynamic range, the spatial, and the frequency resolution of the methods and apply them to complex problems like the analysis of tonal sources with strong directivities or coherent and spatially distributed sound sources. The partners want to jointly develop and validate these methods, exploiting the synergy effects that arise from such a partnership. Beuth plans to extend the equivalent source method in frequency domain to moving sources located in a halfspace, taking into account the influence of the ground and sound propagation through an inhomogeneous atmosphere. ARI contributes acoustic holography, principal component analysis, and independent component analysis methods and wants to use its experience with pass-by measurements for trains to improve numerical boundary element methods including the transformation from fixed to moving coordinates. TUB develops optimization methods and model based approaches for moving sound sources and will contribute its data base of fly-over measurements with large microphone arrays as test cases. EMPA contributes a sound propagation model based on TimeVariant Digital Filters with particular consideration of turbulence and ground effects and will also generate synthetic test cases for the validation of sound source localization algorithms. The project is planned for a period of three years. The work program is organized in four work packages: 1) the development of algorithms and methods, 2) the development of a virtual test environment for the methods, 3) the simulation of virtual test cases, and 4) the application of the new methods to existing test cases of microphone array measurements of trains and aircraft.
Contact: Jean Marc Wunderli
Funding: SNF (Lead Agency Project)
Duration: 2020 - 2023

Man - made elastic structures (often referred to as metastructures) are promising in applications where filtering, focusing or channeling of elastic waves is required. Few examples encompassing different length scales include shielding of buildings from seismic waves, enhanced damping of undesired vibrations of industrial machinery, frequency up-conversion or down-conversion.  However, as we head towards metastructure's massproduction, some important limitations associated with their modelling need to be addressed.  In fact, current models of their dynamic response mainly rely on structural periodicity and bulk behavior. The first and main goal of this project is to develop efficient and accurate FEM algorithms able to predict the dynamic response of non-periodic metastructures, embedded into hosting elastic materials.  The second objective of the project is to validate those simulation tools on the dynamic response of aperiodic metastructures, whose tiling involves two or more overlapping periodicities. We envisage the use of (I) model-order-reduction techniques - to mitigate the numerical demand of the proposed metastructures (complex geometries, irregular boundaries) - and (II) topological optimization techniques - to achieve desired dynamic properties. The proposed materials-by-designs will finally be tested experimentally using 3D-printed prototypes.
Contact: Bart Van Damme
Funding:  Empa
Duration: 2019 – 2021

Data Science Enabled Acoustic Design – AADS
Project description:
Contact: Kurt Heutschi
Funding: Swiss Data Science Center
Partner: Swiss Data Science Center, Gramazio Kohler Research - ETH Zürich, Strauss Electroakoustik
Duration: 2018-2020

OSCAr: Acoustically optimized street canyons
Street canyons in urban areas with a high building density exhibit challenging acoustic environments for the residents and passerby. The multiple sound reflections between the opposite facades not only enhance the noise level and consequently noise annoyance, but can also impair speech intelligibility and acoustic comfort.  
Mandated by the Federal Office for the Environment FOEN, Empa is investigating the acoustic quality in street canyons. Thereby, various building arrangements and facades are being simulated. By means of laboratory experiments (i.e. listening tests) it will be investigated and quantified to what extent the building geometry, as well as the facade structure and absorption, influence noise annoyance and acoustic comfort.
Contact: Kurt Eggenschwiler
Partner/Funding: FOEN
Duration: 2019 – 2020

Urban Mining for Low Noise Urban Roads and Optimized Design of Street Canyons
The soundscape of urban situations is often dominated by road traffic noise. In densely populated areas, noise can cause serious health problems and therefore, city planners are seeking for suitable design strategies to improve the acoustical quality of public spaces.
This SNF funded project aims for a multidisciplinary approach to optimize urban roads and street canyon designs. It is structured in four modules:
1) Development of low noise pavements to improve comfort and health of urban dwellers.
2) Identification of waste materials from the urban environment, for the purpose of producing low noise pavements.
3) Exploration of the noise reduction potential by modification of absorption and reflection properties of the surfaces that form urban street canyons and evaluation of the measures from a subjective point of view by auralisation and listening tests.
4) Improvement and extension of existing methods in Life Cycle Impact Assessment based on the results obtained in module 3).
Contact: Kurt Heutschi
Partner/Funding: Empa Road Engineering / Sealing Components Laboratory, ETHZ Ecological Systems Design, SNF
Duration: 2018 – 2021

Implementation of a pilot assisting system for low noise landing procedures at Zurich Airport
This project aims at further developing the pilot assistance system LNAS of the German Aerospace Center DLR, to allow different types of approaches such as Continuous Descent Approach (CDA) respecting the specific environment of Zurich airport (terrain, airspace restrictions, etc.). Taking into account the pilots user requirements, the human-machine interface shall be improved for an intuitive display of the aircraft configuration change and flight mode commands on an approach map. Additionally, the ATC information about the distance to threshold shall be used to optimize the vertical flight profile. In a one-week flight campaign the system will be demonstrated using the DLR Airbus A320 ATRA (Advanced Technology Research Aircraft) with regular airline pilots operating in the Zurich airport environment to reduce noise with optimized approach profiles and aircraft configuration changes. Noise measurements and subsequent single flight simulations with sonAIR based on FDR data will be conducted by EMPA to analyze the potential of this pilot assistance system. An operational trial with LNAS on aircrafts of Swiss Airline and related 3-month noise measurements is an option of this project.  Industrialization of LNAS is the long-term goal after successful demonstration.
Contact: Jean Marc Wunderli
Partner/Funding: SkyLab, DLR, Zurich Airport, skyguide, Swiss Airlines, Swiss Air Force / FOCA, Office of Transport of the Canton of Zurich (AFV)
Duration: 2018 – 2020
SRF-Beitrag "Schweiz aktuell" vom 10.9.2019

Currently the Federal Noise Abatement Commission discusses in the context of a harmonization of noise abatement and land-use planning regulations the following questions: Are negative effects of traffic noise reduced in the presence of local recreational areas? If yes, could an installation or upgrading of such recreational areas be seen as a noise mitigation measure?
FOEN advised Empa to investigate these questions by reanalysing the survey sample dataset of the SiRENE study. To that purpose additional information on general properties, distance and accessibility of recreational areas should be collected and combined with the present dataset.
Contact: Jean Marc Wunderli
Partner/Funding: FOEN
Duration: 2018 – 2020

Mandated by FOEN, Empa is trying to elucidate the role of single noise events and quiet interim phases on annoyance, based on unfocussed listening tests. The results shall be used to discuss whether future rating levels for traffic noise shall solely rely on average levels such as Leq or if they should be complemented by additional correction factors like the number of pass-bys.
Contact: Jean Marc Wunderli
Partner/Funding: FOEN
Duration: 2018 – 2020

Acoustic Characterization of fungi-treated Violins
How does a fungi-treatment of the tone-wood affect the acoustic properties of violins? An experimental investigation of the structure-borne and the radiated sound fields of different violins – treated and untreated – is performed in the anechoic laboratories. A subsequent psycho-acoustic investigation focusses on the perception and endeavors to single out significant acoustic properties of the individual instruments.
Contact: Bart Van Damme
Partner/Funding: Fischli-Stiftung, Allschwil, CH
Duration: 2017 – 2020

Novel Rail Pads for Improved Noise Reduction and Reduced Track Maintenance
The goal of the project is to develop a novel rail pad system that is optimized with respect to both railway noise reduction and protection of the railway superstructure against transient loads and vibrations. The desired property profile of the novel rail pad cannot be obtained with existing materials, but requires tailoring of the structure and function of the rail pad system at multiple levels and length scales.
We will complement experimental methods with state-of-the-art modelling in order, for the first time, to establish rigorous structure-property relationships, and provide detailed guidelines for combined materials selection and device geometry optimization.
Contact: Bart Van Damme
Partners: École polytechnique fédérale de Lausanne EPFL (LMOM, LPAC, LMAF, LTS2, TRACE), SBB
Funding: FOEN
Duration Phase I: 2017 – 2019
Duration Phase II: 2020 -

ARTEM - Aircraft noise Reduction Technologies and related Environmental iMpact
With ARTEM (Aircraft noise Reduction Technologies and related Environmental iMpact), seven EREA members and strategic partners have teamed up with leading European universities and major entities of the European aerospace industry in order to address the technology challenges raised in the call MG-1-2-2017 “Reducing aviation noise”. ARTEM aims at the maturing of promising novel concepts and methods which are directly coupled to new low noise and disruptive 2035 and 2050 aircraft configurations. A core topic of ARTEM is the development of innovative technologies for the reduction of aircraft noise at the source. The approach chosen moves beyond the reduction of isolated sources as pure fan or landing gear noise and addresses the interaction of various components and sources - which often contributes significantly to the overall noise emission of the aircraft. Secondly, ARTEM addresses innovative concepts for the efficient damping of engine noise and other sources by the investigation of dissipative surface materials and liners. The chosen technology concepts offer the chance to overcome shortcomings (as the narrow band absorption peak or poor low-frequency performance) of current devices. The tasks proposed will mature, and subsequently down select these technologies by comparative testing in a single relevant test setup. Furthermore, noise shielding potential for future aircraft configurations will be investigated. The noise reduction technologies will be coupled to the modelling of future aircraft configurations as the blended wing body (BWB) and other innovative concepts with integrated engines and distributed electrical propulsion. The impact of those new configurations with low noise technology will be assessed in several ways including industry tools, airport scenario predictions, and auralization. Thereby, ARTEM constitutes a holistic approach for noise reduction for future aircrafts and provides enablers for the expected further increase of air traffic.
Contact: Jean Marc Wunderli
Project partners: DLR, AEDS, Airbus, CIRA, CNRS, Comoti, Dassault, EC Lyon, EPFL, ONERA, INCAS, PPS, RRD, SAE, SOTON, TSAGI, TUBS, TUDelft, UBristol, UCP, URoma3, VKI
Project funding: EU – Horizon 2020
Duration: 2017 – 2021

TraNQuIL - Transportation Noise: Quantitative Methods for Investigating Acute and Long term health effects
The overall aim of TraNQuIL is to obtain a thorough understanding on how transportation noise affects human health. In particular, the following research questions will be addressed:

  1. How relevant is eventfulness of noise and duration of quiet phases between events for cardiovascular mortality, and adolescents’ cognitive performance, behaviour and quality of life?
  2. How crucial is noise exposure at different times during day and night for these outcomes?
  3. How relevant is noise exposure at home vs. school for adolescents’ cognitive performance, behaviour and quality of life?
  4. Are noise induced cardiovascular risks reversible after noise exposure reduction? If yes, what is the relevant time scale?
  5. Do noise events trigger an acute cardiovascular death?

Research will be based on the existing Swiss National Cohort (SNC) and adolescent HERMES cohort study. Nationwide models for road, railway and aircraft traffic noise as well as NO2 exposure at each address in Switzerland for 2001 and 2011 will be individually linked to study participants. For HERMES participants, a longitudinal analysis will be conducted to evaluate the effects of noise exposure at school and home on changes in cognitive function, behaviour and health related quality of life within one year of follow-up. Full residential history available after 2010 for the SNC will be used to elucidate the effects of a sudden change of exposure on cardiovascular mortality. A case-crossover analysis on the triggering effects of aircraft noise on acute coronary events in the population around Zürich airport will be conducted, taking advantage of the daily distribution and variation of noise exposure which is heavily influenced by meteorological conditions.
Contact: Beat Schäffer
Project partners: Swiss TPH
Project funding: Swiss National Science Foundation
Duration: 2017 – 2021

Noise Protection in Wooden Buildings
Complaints about noise intrusion from neighboring dwellings, especially from people walking, are still a major problem in multi-family wooden buildings.  The goal of the project “Noise Protection in Wooden Buildings” lead by Lignum and in collaboration with Empa and the Bern University of Applied Sciences is to improve acoustic comfort in modern multi-family wooden buildings in Switzerland by generating knowledge on the airborne and impact sound insulation and disseminating it for the engineers and planers.  The role of Empa’s Laboratory of Acoustics/Noise Control within this project is the experimental investigation of sound transmission through building elements and in mock-ups of typical Swiss wooden buildings in the lightweight construction sound transmission research platform and the analysis of the data. Further, Empa post-processes the data for the use as input data for engineering models for the prediction and optimization of airborne and impact sound insulation. Empa derived simplified engineering models from prediction models for heavy construction, such as concrete and masonry that are well established in Europe. These models can be applied by practitioners and engi-neers already in the stage of design of wooden buildings. The project is funded by the “Aktionsplan Holz” of the Swiss Federal Office of the Environment (FOEN) and a consortium of industry partners.
Contact: Stefan Schoenwald
Project partners: Lignum, BFH-AHB, Industriepartner
Project funding: Lignum
Duration: 2016 – 2020

Dr. Reto Pieren

Dr. Reto Pieren
Head of Group Environmental Acoustics

Phone: +41 58 765 6031

Dr. Andrea Bergamini
Head of Group Materials & Systems

Phone: +41 58 765 4424