MIT OpenCourseWare http://ocw.mit.edu MAS.160 / MAS.510 / MAS.511 Signals, Systems and Information for Media Technology Fall 2007 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.� MAS 160/510 Problem Set Two 1. Phase and Time shifting. DSP First 2.17(a) 2. Switching between frequency-domain and time-domain (a) DSP First 3.2 (b) DSP First 3.3(a),3.3(b) 3. Fourier Series Determine the Fourier series for the following periodic signals of period To: (a) x(t) = t2, 0 ≤ t < To (b) x(t) = t, 0 ≤ t < To/2 1, To/2 ≤ t < To For the following lab exercises (found in Appendix C of the DSP First text), please turn in a hard copy of your functions. 4. DSP First Lab 3 You only need to synthesize one of the 5 musical pieces given (your choice). Items to be turned in: (a) Your note function. (b) Your play scale fuction. (c) A function that outputs sound for one of the given musical pieces. (d) (MAS.510) Now that you have listened to your synthesised notes, aren’t the transitions between different notes very choppy and abrupt? Generate a function that outputs the same piece of music you had selected in (c) but with a smoother transition or basically gives the notes a nice fade. Hint: make a mathematical expression or function that degrades the magnitude of the note against time. 15. DSP First Lab 4 You only need to synthesize one of the FM instruments (bell or clarinet). Items to be turned in: (a) Your mychirp function (this should look familiar :). (b) Your beat function. (c) Plots and answers to questions specified in C.4.3.3. (d) Either your bellenv and bell functions, or your woodwenv and clarinet functions. 6. Additional problem (for MAS.510) Playing with sounds in your envoironment (a) Record a simple “pure” tone. Choose any length of time you desire. Plot the sound in time and also using a spectrogram (use the specgram function in MATLAB). Try to determine the dominant pitch in the simple tone and justify how it was determined. (b) Record your favorite piece of music or any sound for a time duration of 2 secs(in wav format, using wavread command in MATLAB). Plot the spectrogram of the sound you just recorded. Suggest a way in which you could determine the pitch from the spectrogram if you didn’t know what it was to begin with.
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