Engineered wood composites with enhanced acoustic

In the course of the current climate crisis, there is an increased use of wood as a building material. Due to the low weight of the components, achieving a high level of impact sound insulation is a challenge in wooden structures. Concentrating on existing, standardized methods and parameters with an insufficient interconnection with human perception is not a satisfactory approach that comprehensibly characterizes the nuisance caused by impact sound sources. A recent approach that bypasses these imponderables is to recreate virtual built environments. This approach allows the simultaneous investigation of different noise signals and the inclusion of artificial environments without the need to actually build them. This project brings together a multidisciplinary team of established scientists with proven knowledge in the fields of wood-based materials, sound field analysis, building acoustics, modelling and perception assessment. Perception can no longer be condensed to a single number (the so called weighted impact sound pressure level), which is based on outdated methods and a low structural diversity of building components. Thanks to novel recording technologies, their unique combination and mathematical modelling, together with advanced methods for the analysis and interpretation of human perception, a holistic understanding of the acoustic and vibrating interrelationship between building and occupant can be created. The project results provide the basis for the development of highly efficient floating floors and impact sound insulation materials with high acceptable point load and low dynamic stiffness (beneficial for protection against impact sound) from renewable materials. In addition, the unique combination of sound and vibration in the reception and reproduction of the stimuli results in more authentic artificial environments for the subjects in the laboratory. This new approach to perception studies leads to a realistic environment for hearing and vibration testing to determine new targets for evaluating development success. Additionally, advanced measurement and simulation methods will be developed to support an effective future research and development process for these structures by generating virtual stimuli to quantify the performance of these new constructions based on the realistic impact of walking noise nuisance for occupants.

The current climate crisis has led to increased use of wood as a building material. Due to the low weight of the building elements, achieving high impact sound insulation is a challenge. Currently, impact sound insulation is usually achieved through the combination of floating floors and impact sound insulation. The difficulty lies in recording the noise caused by impact sound realistically and reproduce it for test subjects to evaluate. Such recordings help develop an ecological impact sound insulation system and at the same time, a cost-effective system for recording vibrations. In the research project, both the noise and the vibrations caused by the "standard walker" were recorded, synchronized and then played back to test subjects in the laboratory to assess subjective annoyance. The acoustic recordings were done by the Austrian partners using various Ambisonics systems and a low-noise microphone as a reference. Commercial systems and self-developed one were used for parallel vibration measurement. Ambisonics is a method to record sounds with a multitude of microphones. This allows the sound to be reproduced in another environment exactly as it was recorded. The annoyance assessment of the different setups was carried out using 64 spherically arranged loudspeakers plus a subwoofer and a specially developed "vibration plate", which transmits the recorded vibrations to the seat of the test subject located in the center of the loudspeaker sphere. This combination of sound and vibration is unique to date and initial evaluations indicate that the vibrations do indeed influence the test subjects' assessment of disturbance. In parallel, during this research project, the Slovenian partners developed a new type of wood-based impact sound insulation, which was also included in the investigations (initially in the laboratory using sound and vibration recordings of the standard walker) and ultimately patented. The building acoustic performance of this new type of impact sound insulation was investigated at the TU Wien test facility using both standardized and in-depth scientific methods and compared with conventional solutions for decoupling floating screeds. Based on the data obtained, models and findings on impact sound excitation and transmission in these floor systems were developed. In addition, work was carried out on the further development of measurement techniques for determining dynamic stiffness-a key category for evaluating impact sound insulation-as existing standard methods are not yet sufficiently suitable for innovative materials. The IBO developed its own vibration recording system based on inexpensive and readily available standardized electronic components and a simple audio interface from a hi-fi retailer. In the construction sector, this can be used in tasks that require a large number of sensors, such as determining the vibration reduction index of components, which is needed to predict sound insulation in buildings.