Q.1
What role does newSample play in this program?
Same as in increase volume of sound project: Stores the new (multiplied) samples
Stores the indices of multiplied samples
Stores indices before multiplication
Doesn't really play a role
Q.2
What would happen if you didn't copy all the samples when you increased the volume?
Depends - there are so many samples per second that missing a few might not degrade the sound that much. Or it might change the frequency.
Would make the sound louder
Would make the sound softer