Abschlussarbeit

Kontinuierliche Messung von Raumimpulsantworten mit Kugellautsprecherarrays

Bachelorarbeit von Palenda, Pascal

The results of a room impulse response (RIR) measurement are used in acoustic research for auralization, room reflection analysis or sound field analysis. When measuring a single RIR, the measurement system has an intrinsic directivity. Under the assumption that the room complies with the linear-time-invariant-system (LTI-system) prerequisites, superposing single RIRs, taken at specific directions, can synthesize a RIR with arbitrary directivity. The current state of the art is to measure the single RIRs sequentially using a spherical loudspeaker array (SLA) and spherical microphone array (SMA). Nevertheless, hundreds of single RIRs have to be measured for a high-resolution RIR with arbitrary directivity. Due to the long measurement time, the room is subject to changes in temperature and humidity. This in turn invalidates the time-invariance of the assumed LTI-system. The current goal is to minimize the time to complete the measurement. One proposed way is a continuous measurement. With this method the SLA is rotated continuously therefore we can simplify the problem to a measurement with an SLA and a single microphone. RIRs for different spatial directions, corresponding to the sequential measuring direction, can then be extracted from the captured signal. This would in turn eliminate the time of mechanical free travel and oscillations caused by adjusting the SLA and thus reducing the measurement duration. This thesis will examine the viability of continuous measurements for RIR measurements. A comparison methodology will be explored, subsequently the results of the continuous measurements can be compared to the sequential measurements. Furthermore, this thesis explores the limitations of a continuous measurements. Different excitation signals will be implemented, simulated, measured and post-processed using a single-input multiple-output (SIMO) measurement set-up with an SLA.