1. Addison Wesley is an imprint of © 2010 Pearson Addison-Wesley. All rights reserved. Engineering Computation with MATLAB Second Edition by David M. Smith CHAPTER 14: Processing Sound

2. Copyright © 2010 Pearson Addison-Wesley 1-2 Objectives This chapter discusses the following: ■ How sound is physically recorded and played back, and MATLAB’s internal storage of sound ■ Operations that can be performed with the original time trace ■ The ability to transform the data into the frequency domain, and the physical significance of the transformed data ■ Operations that can be performed in the frequency domain

3. Copyright © 2010 Pearson Addison-Wesley 1-3 Sound Recording and Playback

4. Copyright © 2010 Pearson Addison-Wesley 1-4 “Apollo 13” Speech

5. Copyright © 2010 Pearson Addison-Wesley 1-5 “Gone with the Wind” Speech

6. Copyright © 2010 Pearson Addison-Wesley 1-6 The Complete Speech

7. Copyright © 2010 Pearson Addison-Wesley 1-7 Description of Music

8. Copyright © 2010 Pearson Addison-Wesley 1-8 Assembling a Tune

9. Copyright © 2010 Pearson Addison-Wesley 1-9 Assembling a Tune

10. Copyright © 2010 Pearson Addison-Wesley 1-10 Functionality of the FFT

11. Copyright © 2010 Pearson Addison-Wesley 1-11 FFT Math

12. Copyright © 2010 Pearson Addison-Wesley 1-12 Instrument Analysis

13. Copyright © 2010 Pearson Addison-Wesley 1-13 Adding Sounds

14. Copyright © 2010 Pearson Addison-Wesley 1-14 Muting a Trumpet

15. Copyright © 2010 Pearson Addison-Wesley 1-15 Typical Oil Rig

16. Copyright © 2010 Pearson Addison-Wesley 1-16 Structural Analysis Model

17. Copyright © 2010 Pearson Addison-Wesley 1-17 Structural Analysis Results

18. Copyright © 2010 Pearson Addison-Wesley 1-18 Summary ■ Sounds are read into MATLAB with specific readers that provide a time history and sampling frequency ■ Sounds can be played through the computer’s sound system and saved to disk as a sound file ready for playing on any digital player ■ We can slice and concatenate sounds to edit speeches and change the frequency of the sound to change its pitch ■ We can analyze the frequency content of sound using the Fast Fourier Transform (FFT) ■ We can modify the spectra by adding, deleting, or changing the sound levels at chosen frequencies under certain controlled conditions

19. Copyright © 2010 Pearson Addison-Wesley 1-19 Questions?

20. Copyright © 2010 Pearson Addison-Wesley 1-20