Korr 5
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\noindent The chosen method for noise reduction is the use of an adaptive filter combined with the Least Mean Square algorithm, which is a widely utilized method in this context. The evaluation of the performance is conducted via the Signal-Noise-Ratio (SNR)-Gain, which serves as a metric for the quality of the noise reduction. Several use cases (from simple to realistic) are analyzed to evaluate the output qualitiy under different conditions.\\ \\
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\noindent After confirming the general feasibility of the proposed method in a high-level Python implementation, the algorithm is implemented in C, using DSP compiler instrinsic functions to achieve real-time capability. The performance of the C implementation is then sucessfully compared to the initial high-level variant, showing only minor deviations.\\ \\
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\noindent With a working C implementation in place, a closer look on the achievable performance under full-update settings is taken, which serves as a benchmark-setting for the remaining thesis. The computational cost of the algorithm is evaluated in terms of the needed cycles to compute one audio sample, which can be expressed as a function of the filter length and the update rate.\\ \\
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\noindent With a feasibile equation developed, several noise sources are put under test, to evaluatue the optimal filter length, which is a trade-off between the performance improvement and the computational cost. The ideal filter length is determined at 45 coeffcients, where about 95\% averaged \ac{SNR}-Gain can be achieved.\\ \\
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\noindent With the filter lenght set, the improvement of the algorithm is tackled, both for a benchmark track and different signal/noise scenarios.\\ \\
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\noindent With a feasible equation developed, several noise sources are put under test to evaluatue the optimal filter length, which is a trade-off between the performance improvement and the computational cost. The ideal filter length is determined at 45 coeffcients, where about 95\% averaged \ac{SNR}-Gain can be achieved.\\ \\
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\noindent With the filter length set, the improvement of the algorithm is tackled, both for a benchmark track and different signal/noise scenarios.\\ \\
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\noindent The first approach is a reduction of the update rate. This strategy is able to significantly reduce the needed cycles, but with a simultanious considerable decrease in the SNR-Gain.\\ \\
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\noindent The second approach is an error driven optimization, utilizing the idea of a fixed threshold for the error signal, over which the decision over an upgrade of the filter coefficients is made. This approach turns out to be a success, as it is able to achieve a significant reduction in the needed cycles, while only reducing the SNR-Gain by a small amount.\\ \\
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\noindent Therefore, the error driven optimization approach can be seen as the sucessful result of this thesis, as it is able to further improve an already real-time capable ANR algorithm by significantly reducing the computational load of the DSP core, while only slightly decreasing the performance improvement in terms of the SNR-Gain.\\ \\
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\noindent The second approach is an error-driven optimization, utilizing the idea of a fixed threshold for the error signal, over which the decision over an upgrade of the filter coefficients is made. This approach turns out to be a success, as it is able to achieve a significant reduction in the needed cycles, while only reducing the SNR-Gain by a small amount.\\ \\
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\noindent Therefore, the error-driven optimization approach can be seen as the sucessful result of this thesis, as it is able to further improve an already real-time capable ANR algorithm by significantly reducing the computational load of the DSP core, while only slightly decreasing the performance improvement in terms of the SNR-Gain.\\ \\
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\end{abstract}
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\include{chapter_01}
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