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Midterm Exam 2 Review Fall 2004: Lower or Louder

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For Lower or Louder, is there any formula that will help us find the frequency of each sound? It seems to me that a reasonable answer for part a would be the sampling rate divided by 100 and for part b the sampling rate divided by 200, however, if that is correct I am unsure as to why.
So which would be lower and which higher? Did you try the programs and see which does which? REMOVEDw about how you would figure out the maximum amplitude? Mark Guzdial

what does posn mean? are we spose to know what it means from lecture?
Posn is a variable, you could use anything in the place of all the posn and the program would still do the same thing. In this case, it has been used to represent "i % 200". Student117
have i missed out completely or am i being dumb? i don't recall using % for anything?
hmm i % 200...anyone have a hint where i can find that one in the book???i'd owe you thirty dollars at least.

% is the "Mod" operator. It can be used just like any other arithmetic operation. Experiment in JES to see what it does. Student549
the modulus is the remainder after division. Student2243
b. produces a lower and louder sound than does a.

how do you know if a sound is low?

B sounded low but B was louder.

on Jes, it said that A had a media.sound instance at 5256823 whileB had a media.Sound instance at 25410929. does that mean anything?
That doesn't mean anything in term of the two programs. That's got to do with where the function is stored in memory. Student1594

i mean, A was louder
do the pictures of A and B .wav's look correct? how doi tell which is a louder sound based upon the graphs?
The number after media.Sound is (essentially) the address of where the object sits in your computer's memory (RAM). Louder sounds should have larger amplitude, right? Mark Guzdial

yes, but how do you tell if a sound is lower?

Lower pitch means lower frequency which means fewer cycles per second. Does it SOUND lower? Mark Guzdial

I don't understand how this code made the pitch lower. Does "value" affect amplitude or frequency?
It affects both. Amplitude being how high it goes up is affected by what you are adding to value (The REMOVED you add, the higher it goes up) Frequency is related to how long it takes to get back to the original value, so for how long are you increasing it before you start decreasing it, and how long will it take to decrease back to it's original value. Student1594
how do you konw the frequency of each sound (question 3)?
btw, amp = 32767/loudest
therefore, the max amplitutde of sound a = 32767/2400
b = 32767/9800

right???
Why divide to compute amplitude? Isn't the amplitude just how high the wave gets at maximum? Mark Guzdial

Ok for the frequencey, I know the index cycle for each but what I do now know is how many indexes per second. I know that the rate of an empty sound was given, but I can not figure out how to use that to determine the number of indexes per second. What am I missing?
Do we use the NYQUIST THEOREM for part c on how to find the frequency. If that's the case, then it should be quite straitforward. Please leave a few tip.
isnt the frequency half of the sampling rate??

because we need twice as many samples as the frequency to recreate the sound
maybe??


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