Doppler effect

[d, sam] = audioread("horn.wav", "native");
#tf = 9;
#disp(sam)
#d1 = d[:tf*sam];
t = ((0:1:length(d)-1)').*1.0/sam;
plot(t, d);
title("audio of a moving sound source")
xlabel("time");
ylabel("waveform")

length(d)

ans =  425984

pkg load signal;
specgram(abs(d), 256, sam, hanning(sam));
colormap('jet')

warning: specgram fft size adjusted to 16000
warning: called from
    specgram at line 152 column 5

[S, f, t1]=specgram(abs(d), 256, sam, hanning(sam));
imagesc(t1, f, log(abs(S))); shading interp;
colormap('jet');

warning: specgram fft size adjusted to 16000
warning: called from
    specgram at line 152 column 5