Matlab高通滤波器

Question

我为我的吉他创建了一个失真踏板，我用高通滤镜创建了一个失真。一切都很有效，除非我注意到随着音符逐渐消失而产生这种噼啪声。

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function audio = reaper(frame, drive, tone)
    % Distortion pedal with high-pass filter and gain.
    %
    %   audio = reaper(frame, drive, tone)
    %
    %   frame: audio frame to be processed (int32)
    %   drive: amount of gain to apply to the filtered signal (between 0 and 10)
    %   tone: cuttoff frequency for high-pass filter (between 0 and 10)
    %
    %   The reaper distortion pedal first sends the signal through a
    %   butterworth filter (high-pass) that sets the cutoff frequency based
    %   on the tone. Then the filtered frequency is multiplied by the drive
    %   (gain). The resulting audio frequency is returned.

    % Use butterworth filter for high-pass filter
    [zeros,poles,gain] = butter(1,265*((tone+(10/9))*(9/10))/(44100/2),'high'); % Tone is normalized between 1 and 10
    [num,den] = zp2tf(zeros,poles,gain);
    
    % Apply high-pass filter with gain
    audio = int32(((drive+(10/99))*(99/10))*filter(num,den,double(frame))); % Drive is normalized between 1 and 100
end

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