Performance of a Multichannel Audio Correction System Outside the Sweetspot.: Further Investigations of the Trinnov Optimizer.
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This report is a continuation of the student project "Evaluation of TrinnovOptimizer audio reproduction system". It will further investigate theproperties and function of the Trinnov Optimizer, a correction system foraudio reproduction systems. During the student project measurements wereperformed in an anechoic lab to provide information on the functionality andabilities of the Trinnov Optimizer. Massive amounts of data were recorded,and that has also been the foundation of this report. The new work that hasbeen done is by interpreting these results through the use of Matlab. The Optimizer by Trinnov [9 ] is a standalone system for reproductionof audio over a single or multiple loudspeaker setup. It is designed tocorrect frequency and phase response in addition to correcting loudspeakerplacements and cancel simple early re?ections in a multiple loudspeakersetup. The purpose of further investigating this issue was to understandmore about the sound?eld produced around the listening position, and togive more detailed results on the changes in the sound?eld after correction.Importance of correcting the system not only in the listening position, butalso in the surrounding area, is obvious because there is often more than onelistener. This report gives further insight in physical measurements ratherthan subjective statements, on the performance of a room and loudspeakercorrection device. WinMLS has been used to measure the system with single, and multiplemicrophone setups. Some results from the earlier student project are alsoin this report to verify measurement methods, and to show correspondancebetween the di?erent measuring systems. Therefore some of the data havebeen compared to the Trinnov Optimizer's own measurements and appear similar in this report. Some errors found in the initial report, the results from the phase response measurements, have also been corrected. Multiple loudspeakers in a 5.0 setup have been measured with 5 microphones on a rotating boom to measure the soundpressure over an area around the listening position. This allowed the e?ect of simple re?ections cancellation, and the ability to generate virtual sources to be investigated. For the speci?c cases that were investigated in this report, the Optimizer showed the following: ? Frequency and phase response will in every situation be optimized to the extent of the Optimizers algorithms. ? Every case shows improvement in the frequency and phase response over the whole measured area. ? Direct frontal re?ections was deconvolved up to 300Hz over the whole measured area with a radius of 56cm. ? A re?ection from the side was deconvolved roughly up to 200Hz for microphones 1 through 3, up to a radius of 31.25cm, and up to 100Hz for microphones 4 and 5. ? The ability to create virtual sources corresponds fairly to the theoretical expectations. The video sequences that were developed give an interesting new angle on the problems that were investigated. Other than looking at plots of di?erent angles which is di?cult and time consuming, the videos showed an intuitive perspective that enlightened the same issues as the common presented data of frequency and phase response measurements.