clear all 
close all
pkg load signal
[y,fs] = audioread('modulator22.wav');
audiowrite('outmodulator22.wav',y,fs/2);
n = length(y); 
t=0:1/fs:(n-1)/fs; % time range
spectrogram(y,fs,5,30);
y=y(floor(0.7*fs):floor(1.15*fs));
[power,duration]=frequencySpectrum(y, fs, false);
spectrogram(y,fs,5,30);