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| This is what the above code does. It takes the Fourier transform (or Fourier series) of f, then plots the amplitudes. The funny code around it is because Matlab places the Fourier transform coefficients in a ' | This is what the above code does. It takes the Fourier transform (or Fourier series) of f, then plots the amplitudes. The funny code around it is because Matlab places the Fourier transform coefficients in a ' | ||
| - | ===== Real sounds ===== | + | That's a lot to take in. You do not have to understand this theory on fft beyond the basic understanding we presented in Lecture 34. |
| - | That's a lot to take in. The rest is about more fun stuff. | + | The rest is about more fun stuff. |
| + | ===== Real sounds from instruments ===== | ||
| + | |||
| + | ===== Tuning music and beats ===== | ||
| + | |||
| + | < | ||
| + | % Example of pitch modification | ||
| + | Fs = 2^13; T = 5; | ||
| + | t = 0:1/Fs:T; | ||
| + | |||
| + | % This is an A note of 440 Hz | ||
| + | fA = sin(2*pi*440*t); | ||
| + | sound(fA, Fs) | ||
| + | |||
| + | %% This is an E note of 659.3 Hz | ||
| + | fE = sin(2*pi*659.3*t); | ||
| + | sound(fE, Fs) | ||
| + | |||
| + | %% We can make our A note sound like an E note | ||
| + | % by essentially changing our definition of ' | ||
| + | % sampling frequency. This is a cheap way of modifying pitch. | ||
| + | sound(fA, 659.3/ | ||
| + | </ | ||