The document describes the steps to design a 10-band software audio equalizer using MATLAB. It involves creating a GUI with 10 sliders, load, reset, play and stop buttons. Callback functions are added to each component to get the slider values and filter the audio. An equalizer plot is also added to visualize the filter response. Finally, 10 filters are designed, one for each band, and the equalizer is tested.

2. Task is to design a 10-band software
audio equalizer.
1/5/2017Audio Equalizer.............................................Hasham_Khan

3.  Open Matlab
 Using “ guide ” function create a new GUI
1/5/2017Audio Equalizer.............................................Hasham_Khan

4.  For 10 bands Audio Equalizer we need 10 sliders…
so select 10 sliders
1/5/2017Audio Equalizer.............................................Hasham_Khan

5.  After the completion of previous step your design will be like this ;
1/5/2017Audio Equalizer.............................................Hasham_Khan

6.  Define the values for each slider handles
• global stop C Fs;
• stop=1;
• Fs=44100;
• C=zeros(1,10);
Slider 1 values are as follow;
• set(handles.slider1,'min',-20);
• set(handles.slider1,'max',20);
• set(handles.slider1,'value',0);
• set(handles. slider1,'SliderStep',[0.025,0.05]);
• set(handles. slider1,'string',num2str(0));
Repeat the above steps for all 10 Sliders
1/5/2017Audio Equalizer.............................................Hasham_Khan

7.  Double click on each slider and click “ callback”
and “ CreateFtn ”…By clicking both you will see both functions
in your m file
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8.  To get the different values of slider add “get” function
• % Executes on slider movement.
• function slider1_Callback(hObject, eventdata, handles)
• global C;
• C(1)=get(hObject,'value');
• set(handles.slider1_val,'string',num2str(C(1)));
• % --- Executes during object creation, after setting all properties.
• function slider1_CreateFcn(hObject, eventdata, handles)
• if isequal(get(hObject,'BackgroundColor'),
get(0,'defaultUicontrolBackgroundColor'))
• set(hObject,'BackgroundColor',[.9 .9 .9]);
• end
Repeat the above steps for all 10 sliders
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9.  To add “Load”, “ Reset ”, “ Play ” ,“ Stop ’’ buttons use the Push button
in the GUI
 Double click on Push button and change the string and tag as load , reset ,
play and stop.
1/5/2017Audio Equalizer.............................................Hasham_Khan

10.  Now after adding the button your design will be like this ;
1/5/2017Audio Equalizer.............................................Hasham_Khan

11.  Double click on each button and select callback function
For Reset button :
• set(handles.slider1_val,'string',num2str(0));
• set(handles.slider1_var,'value',0);
Repeat the above step for all 10 sliders
For Load button :
• % -Executes on button press in load.
• function load_Callback(hObject, eventdata, handles)
• global file_name;
• file_name=uigetfile('*wav','hasham .wav');
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12. For Stop and Play Button :
• % --- Executes on button press in play.
• function play_Callback(hObject,
eventdata, handles)
• global stop file_name C;
• stop=1;
• equalizer_play();
• function equalizer_play()
• global stop file_name C;
• [x,Fs]=wavread(file_name);
• [a,b]=coef();
• l_bucata=2*Fs;
• Nb=round(length(x)/l_bucata);
• y=0;
• for i=1:floor(Nb)
• bucata=x((i-1)*l_bucata+1:i*l_bucata);
• for k=1:5
• y=y+filter(10^(C(k)/20)*b{k},a{k},bucat
a);
• if(stop==0)
• break;
• end
• end
• wavplay(y,Fs,'async');
• y=0;
• if(stop==0)
• break;
• end
• end
• % --- Executes on button press in stop.
• function stop_Callback(hObject, eventdata,
handles)
• global stop;
• stop=0;
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13.  Add Edit Text to each slider and double click the edit text icon and select
“callback” and “CreateFtn” for each slider
1/5/2017Audio Equalizer.............................................Hasham_Khan

14.  After adding the edit text to each slider your design will be like this ;
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15.  To have the value of each slider add the below code to each slider;
 function slider1_val_Callback(hObject, eventdata, handles)
 global C;
 C(1)=str2num(get(hObject,'string'));
 minn=get(handles.C1_var,'min');maxx=get(handles.C1_var,'max');
 if(C(1)<minn || C(1)>maxx)
 C(1)=get(handles.C1_var,'value');set(hObject,'string',num2str(0));
 else set(handles.slider1_var,'value',C(1));
 end
 function slider1_val_CreateFcn(hObject, eventdata, handles)
 if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
 set(hObject,'BackgroundColor','black');
 end
Repeat the above step for all 10 sliders
1/5/2017Audio Equalizer.............................................Hasham_Khan

16.  Add equalizer plot and filter function in the code. As the equalizer is of
10 band so we have to design 10 filters.
1/5/2017Audio Equalizer.............................................Hasham_Khan

17.  After adding the equalizer plot your design will be like this ;
1/5/2017Audio Equalizer.............................................Hasham_Khan

18.  So your design of 10 Band Audio Equalizer is ready now run the code
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19. Thank You
Prepared by
Hasham Khan
hkhan.msee16seecs@seecs.edu.pk
NUST School of Electrical Engineering and Computer Science(SEECS)
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