i want frequency domain spectrum of an audio file but i am getting amplitude range upto 0-6000. how can i normalize it? sampling rate is 48kHz

[y,fs,nbits]=wavread('C:\Users\HP\Desktop\s1.wav');

N = length(y);

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

plot(f,abs(yfft));