Question 1 Read the "dtmf.wav" audio file using audioread function of MATLAB. Identity the corresponding 4-digit dialed number. Show all your work and plot the Short-time Fourier Transform the DTMF digits ("spectrogram" or "specgram" in MATLAB). Please use a window size of 256 to estimate the digits. DTMF Frequency Table: Frequencies 697 Hz 770 Hz 852 Hz 941 Hz 1209 Hz 1 4 7 1336 Hz 2 5 8 0 For example, the digit 5 is "encoded" in a phone as follows: x5 (t) = cos(271336t) + cos(2 770t) 1477 Hz 3 6 9 # 1633 Hz ABC D Question 2 a) Calculate the pitch period of "a" of your "Washington" sound using the autocorrelation method and plot the autocorrelation function. b) Calculate the pitch period of "o" of your "Washington" sound using the autocorrelation method and plot the autocorrelation function. c) Calculate the pitch period of "o" of your "Washington" sound using the spectrum of the speech segment and plot the magnitude of the FFT.