how to add plot values for many iteration

Hi all, i wonder if anyone could help me. I have this codes where it plots a function from x-axis values from 1 to 500. The graph has this x and y axis.

I repeat this plot for many locations (coordinate), I was able to get all the plot for 32x4 coordinates.

However I want to add all this plots (the y-axis values) and just have one final plot for all the coordinates (in the codes the coordinates are represented by w and g letters). It is like I add the y-values every time for all the coordinates. How can I do that?

   for w=3:2:9 

   for g=1:32

 z=(w-2)*dz0; % 4 points laterally
 theta=g*dtheta0; % 32 points circumferentially

%step from 1 to 500

for fi=1:500

    .........
    ................

      pressurey(fi)=(si1)*small_ay;

%plot

      SPL(fi)=abs(pressurey(fi));

      end

      freq=1:500;
      plot(freq,SPL,'b')
      hold on

       end
    end