NPB 163/PSC 128

Lab #5 - Music and sound synthesis

(due Friday, 2/6)

1. Divide the octave into two different frequency scales:  one linear and the other logarithmic.  Play each of your scales using 'soundsc'.  Which sounds more evenly spaced?  Why?  (Use a 'for' loop to sequence through the scale and 'pause' to put a break between notes.)

2. See if you can confirm "Plomp's curve" by playing two pure tones separated in frequency by different amounts.  At what point does the combination sound most dissonant?   (Again, use a for loop and pause to loop through your tone combinations.)

3. Reconstruct one of the sentence waveforms using the same method of Fourier synthesis as in the last assignment.  Then, break the waveform into a sequence of blocks and try randomizing the phase within each block.  Then try randomizing the amplitudes (keeping the phase intact).  Which is more important, amplitude or phase?  What is the dependence on block size?

4. Create five different stereo pairs of sinewaves that would result in the percept of being localized to five different locations: far-left, left-of-center, center, right-of-center, and far-right.  Play these through earphones (read the help on 'sound' to find out how to play stereo).  Do they sound like they are coming from different locations?  (You will need to calculate the maximum time delay necessary to create the percept of far-left or far-right, and then translate this into a phase shift for whatever frequency you use.  The frequency should be below 1000 Hz.)