Research And Implementation Of Audio Equalizer Algorithms

Audio Equalizer is one of the most important technologies of the professional audio industry, but in the classical equalizer design, the frequency resolution is relatively low, so the influence of two adjacent bands is usually unacceptable, and the user of the equalizer can not fix the problem of frequency response curve accurately.In this thesis, a new method called high-order equalizer, which can eliminate the overlap of two adjacent bands, is present. The proposed algorithm makes up the disadvantage of the classical equalizer algorithm. Such design can provide flatter passbands and sharper bandedges at the expense of higher computational cost. Fistly in this thesis some key technologies realated to audio equalizer are introduced; then the algorithm of high-order equlizer is proposed by analyzing some algorithms which are commonly used. In the test part of this thesis, the algorithm of high-order equlizer and some different filter structures are tested. In the test of stringent and time-varying filter specifications, the Frequency-shifted transposed design performs well, so the frequency-shifted transposed design is chosen for the realization of the filter sections in the finally designed audio player.The results of the testing the algorithm of high-order equalizer have shown that the algorithm performs well for the overlap problem, but the phase property is not linear, so further study and analyse should foucus on it.