Write Matlab code to do the following: Low pass filter the signal using an FIR filter with cutoff frequency 400 Hz (a filter of

order 20 will suffice). Use the window method to design the filter (remember that the cutoff frequency is expressed in normalized form).

For each frame of length 32 msec, calculate the autocorrelation function for the signal. Assume the pitch falls in the range 80 Hz to 180 Hz. From the expected pitch range, calculate the minimum and maximum lags expected. Hint: convert the maximum and minimum expected pitch frequency values into their corresponding pitch period values in samples (remember these have to be integer values so will need rounding), and limit the range of analysis to these values remember the reciprocal relationship between time and frequency!