added function

src/Meghaj_Echo.m

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+% Meghaj_Echo: input a wave (in time domain) and a frequency to induce an 
+% echo/lag effect to. The outputted wave amplifies frequencies above the 
+% cutoff and creates an echo in the frequencies below the cutoff creating 
+% a beat lag effect. Inspired by "muffled_effect_schluep" and lecture notes
+% Works best on songs that have a clear snare line with a frequency of 
+% HIGH = 1000. Use on song files like "Strong-Bassline.mp3"
+
+% CONTRIBUTORS:
+% Meghaj Vadlaputi: Function Author
+
+
+
+function y = Meghaj_Echo(x, HIGH)
+    len = length(x);
+    X = fft(x);
+    X = fftshift(X);        %Fourier transform the input wave
+    Y = zeros(1, len);
+    
+    for ind = 1:len
+        %Multiplying the Fourier transform in frequency domain by e^jw(0.05)
+        %to induce a time shift of 0.05 seconds creating the "lag" effect on
+        %frequencies below HIGH (HIGH = 1000 works best)
+        %Multiplying the remaining signal by 1.25 amplifies other
+        %frequencies to balance
+        if abs(X(ind)) < HIGH
+            Y(ind) = X(ind) + 0.5*(X(ind)*exp(1i*ind*0.05));
+        else
+            Y(ind) = 1.25*X(ind);
+        end
+    end
+    
+    
+    Y = fftshift(Y);
+    y = ifft(Y);
+    y = real(y);
+        
+end