4. Audio Signal Visualization. Download and load into MATLAB the file FinalProblem4.mat.This files contains a vector y of audio samples and a sampling frequency Fs. If you want you can

listen to the file. a) How long is the audio signal in seconds? b) Plot a one sided amplitude normalized spectrum of the audio signal, The x axis should be in Hz. c) Plot a time-frequency spectrogram of the audio file using a 1024 length window, 50% overlap,and a 1024 length fft. Use the same format of the spectrogram function call we have used in class and on homework assignments (this format is also presented in the textbook). The frequency should be on the y-axis.