Am 21. Januar 2022 hat Herr Ingo Witew seine mündliche Promotionsprüfung erfolgreich abgeschlossen.
Herr Witew promovierte über das Thema:
„Measurements in room acoustics – Uncertainties and influence of the measurement position“
Abstract:
Regardless of the field, measurements are essential for the validation of theories and for making well-founded decisions. A criterion for the validity and comparability of measured values is their uncertainty. The „Guide to the Expression of Uncertainty in Measurement“ (GUM) provides a standardized framework for determining and interpreting measurement uncertainty. In room acoustic measurements, the application of these rules is not yet widespread. On the one hand, this is due to the fact that well established 2-CH-FFT correlation techniques rely on a complex principle, which is not covered by the classical guide. In addition, the effect of input variables on a measurement can only be determined in individual cases after considerable effort. An example are fluctuations of room acoustic quantities over smallest distances between measurement locations in concert halls. This change of the sound field over the location is sometimes considerable and can only be predicted in relatively simple boundary value problems. This raises the question of the validity and interpretability of room acoustics measurements.
The goal of this thesis is to provide a GUM-compliant discussion of uncertainties in measuring room acoustic single-number quantities. This starts with a structured search of variables that potentially influence the measurement of room impulse responses. In a second step, this uncertainty is propagated through the algorithm for determining room acoustic single-number quantities.
Further emphasis is placed on the investigation of spatial fluctuations of the sound field in auditoria. The influence of an uncertain measurement position on the overall measurement uncertainty is discussed. To reach general conclusions, the relation between changes in the measurement location and the corresponding changes in room acoustics quantities is investigated empirically in extensive measurement series. To this purpose, a measurement apparatus was designed that allows automatic, high-resolution sampling of sound fields over large areas. The collected data sets the foundation to propagate the uncertainty using a Monte Carlo method.
This study shows how precisely a measurement position must be defined to ensure a given uncertainty of room acoustical single-number quantities. The presented methods form a foundation that can be flexibly extended in future investigations to include additional influences on the measurement uncertainty.
Das IHTA gratuliert sehr herzlich!!
Fotos: Josep Llorca-Bofí
