% ex36.m
srate=11025;            % sample rate
nsamp=2*srate;          % number of samples
t=0:2/nsamp:2;          % sample times
f=250:750/nsamp:1000;   % required frequency at each sample time
y=sin(2*pi*f.*t);       % OK provided change in f per sample is small.
sound(y,srate);