how to get max frequency and how to get frequency response for 0.5 seconds wav file by using following code?

this is the code in which I need frequency response for 0.5 seconds and how to set xlim and max frequency ?

[y,fs]=audioread('filename.wav);

Nsamps = length(y);

t = (1/fs)*(1:Nsamps)

% do fourier transformer

y_fft= abs(fft(y));

y_fft= y_fft(1:Nsamps/2);

f=fs*(0:Nsamps/2-1)/Nsamps;

%plot sound file in Time domain

figure

plot (t, y)

xlabel('Time (S)')

ylabel ('amplitude')

title('file name in Time Domain')

%plot sound file in frequency domain

plot(f, y_fft)

xlim([0 1000])

xlabel('frequency(HZ)')

ylabel('amplitude')

title('frequency response of song')