After the experimental procedure was completed on Thursday the 25th of July, the anechoic chamber was emptied as it was booked by other parties to conduct different measurements. In the meantime, the project entered the analysis stage. Before isolating and examining the reflected peak I created a MATLAB script responsible for importing all the Impulse Responses (IR) obtained from the experimental procedure, storing them into structures and plotting them in the time domain.
When analysing the plots, the IRs seemed consistent. As expected, the different takes obtained from the same angles appeared to be almost identical following consistent patterns as the microphone moved around the trunk. Unfortunately, even though the measurements were obtained with much care at a high degree of accuracy, the graphs of the IRs of the smaller angles, were the microphone was the closest to the loudspeaker presented 3 peaks, suggesting that there was an unwanted reflection. After studying carefully the setup, two potential causes were considered:
- There was feedback on the microphone
- There was an unwanted reflection due to an exposed hard surface
Since the anechoic chamber is currently unavailable the measurements can not be repeated. As a result, the next weeks will be used to see whether this unwanted peak can be ignored or even eliminated by editing the IRs on MATLAB.
Figure: Plot of the IR showing the unwanted peak and the reflection from the trunk
George Sarantinos 