Karl, Tim

This thesis presents a multidisciplinary research framework for the design, analysis, optimization, and experimental validation of both passive and Active Noise Control (ANC) strategies applied to the HafenCity window system. The increasing urban density and the associated rise in environmental noise call for novel and effective noise mitigation strategies in building façades. Addressing this challenge, the present work combines acoustics, mechanical engineering, signal processing, and adaptive control to develop an integrated, modular, and scalable system capable of reducing sound transmission through complex window structures. The core of the study is a laboratory demonstrator which serves as a flexible test environment for the iterative development of both passive and active measures. The initial part of the work is dedicated to a review of state-of-the-art technologies in sound reduction and ANC systems, highlighting their respective limitations and research gaps. Building upon these insights, a laboratory demonstrator integrated into a transmission test rig is constructed to enable controlled and repeatable investigations of acoustic behaviour under variable conditions. The demonstrator incorporates modular absorber components, actuators, and microphones, allowing for flexible adaptation to different configurations. Acoustic system characterization is conducted using several complementary measurement techniques, including sound reduction index determination according to standardized procedures, modal analysis of the transmission test rig, different system identification methods, and vibration measurements of the window structure. Advanced signal processing techniques, as the generation and deconvolution of exponential sine sweep signals, are employed to extract detailed information on the system's impulse response, transfer paths, and non-linearities. Additionally, metrics such as Reverberation Time (RT), spatial diffuseness and Total Harmonic Distortion (THD) are evaluated to quantify the acoustic performance and dynamic properties of the system. Subsequent chapters focus on the design, optimization, and experimental validation of passive absorber elements within the window cavity. Methods such as sound field mapping are used to visualize standing wave patterns and optimize absorber placement and geometry. Sensor and actuator positions are optimized using both numerical methods and heuristic algorithms, targeting improved controllability and performance of the ANC system. A validation strategy is presented that includes both simulation-based predictions and experimental testing, confirming the robustness of the optimization approach. Another contribution of this work is the implementation of adaptive control algorithms, specifically FeedForward (FF) and FeedBack (FB) variants, for real-time noise cancellation. These algorithms are tested under various boundary conditions, including varying delays, non-stationary excitation, and secondary path variability. Performance parameters such as quiet zone formation, real-time attenuation, spatial resolution and latency are analysed. Results show that reductions in transmitted noise levels are achievable confirming the applicability of ANC in façade-integrated systems. Last the development of an ANC prototype incorporates hardware components selected for embedded operation, including Micro-Electro-Mechanical-Systems (MEMS) microphones, miniaturized amplifiers, loudspeakers, and two real-time processing platforms, a Digital Signal Processor (DSP) and a Field-Programmable-Gate-Array (FPGA). Both platforms are benchmarked with respect to latency, computational power, implementation complexity, and scalability. Comprehensive experimental evaluations demonstrate that the integrated system achieves improvements in broadband noise attenuation, particularly within the lower frequency range where passive elements are less effective. In conclusion, the research demonstrates that window systems with embedded ANC functionality offer a viable path forward in mitigating environmental noise in urban architecture.