clear;

FS=8000;

x1 =loadwave('tone0.wav');
x3 =loadwave('tone2.wav');
x5 =loadwave('tone4.wav');
x6 =loadwave('tone5.wav');
x8 =loadwave('tone7.wav');
x10=loadwave('tone9.wav');
x12=loadwave('tone11.wav');

x=[x1, x3, x5, x6, x8, x10, x12];

x=convol([-0.4, 0.0, 1.0, 0.0, -0.4], x);     // FIR BPF
x=0.95*x/max(abs(x));
savewave('scaletone.wav', x, FS);