Matlab Course Project Code

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• First import the sound data with drag and drop to matlab in Matlab
• %data = sound-data
• %fs = Samplingrate
• %check the spectrogram of the given sound-sample;
• spectrogram(data,1024,512,2048,fs,'yaxis');
• %detect the corner frequency of the noise (example ~5500 Hz)
• %build a lowpasses with corner frequency of 7500 Hz
• Fn = fs/2;
• fc = 7500; %Herrausgefunden Grenzfrequenz
• lpass = fc/Fn*sinc(fc/Fn*(-200:200)).*blackman(401)';
• figure;freqz (lpass,1,1024,fs);
• %Begutachten und zur not das Blackman window vergrößern um eine besser steilheit zu bekommen
• %daten durch den filter jagen
• data1 = filter(lpass,1,data);
• figure; spectrogram(data1,1024,512,2048,fs,'yaxis');
• %Ton gefunden bei 650Hz erstellen eines neuen bandstop filters
• %bandbreite etwa 100Hz
• f0 = 650; %Mittlere Frequenz des Bandstopfilters
• deltaf = 100; %delta um den frequenzpunkt
• omega0 = f0*2*pi/fs;
• aa = deltaf*pi/fs;
• zz = exp([j;-j]*omega0);
• pp = zz*(1-aa);
• bb = poly(zz);
• aa = poly(pp);
• figure; freqz(bb,aa,1024,fs);
• %daten durch den filter jagen
• data2 = filter(bb,aa,data1);
• figure; spectrogram(data2,1024,512,2048,fs,'yaxis');
• %stöhrgeräusch von 0-100hz entfernen
• f0 = 0;
• deltaf = 200; %delta um den frequenzpunkt
• omega0 = f0*2*pi/fs;
• aa = deltaf*pi/fs;
• zz = exp([j;-j]*omega0);
• pp = zz*(1-aa);
• bb = poly(zz);
• aa = poly(pp);
• figure; freqz(bb,aa,1024,fs);
• data3 = filter(bb,aa,data2);
• figure; spectrogram(data3,1024,512,2048,fs,'yaxis');
• %lauter machen und abspielen
• sound(data3*50000,fs);

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