How does sound frequency work?

[Jjoshua2]

So I have an extra credit project to change the frequency of a wav file. The main part was to reverse it, and that was easy, but I'm not sure how to do the extra credit. I know if I speed it up it will be higher pitch, but I think I am supposed to keep the length the same.
So they give me a recorded note (not synthetic) and I create higher notes to create an octave scale. I am given the wav file in converted form to be at each time an amplitude of the analog wave between -1 and 1.

Thanks for any insights!

EDIT: So I don't have much information, just this. Assuming that your .dat input file contained a single note, try writing a program which will output a single-octave scale beginning at that note. To earn full credit, you must start from an actual recorded note (not a synthetic one) and generate the single-octave scale.

I could decrease the period between the samples, but that would make the scale get faster as it went up, and I think each note should be the same length. This is a programming class, so I don't know much math or music theory. I'm guessing that Fourier transform is what I want to do. Any pointers for a little more info on how to do that on discrete data plot?
http://en.wikipedia.org/wiki/Audio_timescale-pitch_modification It looks like there are three ways, but it seems any but the first is way to complicated for me, since this extra credit is due in like a week and I have other classes.

 

[PottedMeat]

increase/decrease the period between samples?

 

[theflyingpig]

Pathetic. You come here asking for help, and you don't even have the decency to tell us what it is you need help with.

 

[ShawnD1]

Do a fourier transform on the wave to find what the component waves are. Change the frequency of each individual wave. Recombine the components.

If you're using a piece of software, it should have a simple + or - pitch control.

 

[Rubycon]

If you're using a piece of software, it should have a simple + or - pitch control.

Pitch control / preserve duration.

 

[The Stig]

how is babby formed?

 

[Tiamat]

record .wav on cassette tape. Increase speed of cassette tape player.

Reminds me of the time when my dad got his, at the time, new 1996 Chrysler T&C and we popped in a cassette of the Widor's Tocatta (Charles-Marie Widor's Symphony No. 5) and the salesman thought I was crazy when I told him the cassette player was bad. I told him the song is originally played in F major but on the car stereo, it was playing in F# major. He didn't understand a word I was saying, neither did he know what perfect pitch was. Regardless, they swapped the cassette player anyways

 

[Rubycon]

record .wav on cassette tape. Increase speed of cassette tape player.

In the old days we used to hold down the play button about halfway and it would play fast. A 2 hour lecture could be listened to in 22 minutes.

 

[Red Squirrel]

In the old days we used to hold down the play button about halfway and it would play fast. A 2 hour lecture could be listened to in 22 minutes.

I'm the sound guy at our church and I've actually done that to sermons that go over what a CD can hold. I don't want to have to split it in two, so I just speed it up a little. Nobody has noticed or said anything, yet. ()

 

[Tiamat]

In the old days we used to hold down the play button about halfway and it would play fast. A 2 hour lecture could be listened to in 22 minutes.

Oh yeah, good times, although not so old days, i remember doing that during the late 80's early 90's before I could afford a CD player

 

[Tiamat]

I'm the sound guy at our church and I've actually done that to sermons that go over what a CD can hold. I don't want to have to split it in two, so I just speed it up a little. Nobody has noticed or said anything, yet. ()

LOL that is too funny! Since not too many people have perfect pitch, they wouldn't really be able to tell

 

[Hacp]

No equations? What kind of class is this!

 

[Rubycon]

I'm the sound guy at our church and I've actually done that to sermons that go over what a CD can hold. I don't want to have to split it in two, so I just speed it up a little. Nobody has noticed or said anything, yet. ()

All of the recorders I had went pretty fast. I'd imagine unless your churchgoers are chipmunks, they'd notice.

Newer designs have the ability to time compress - shorten the duration without changing the pitch. This is done in TV commercials too particularly with the small print section. You know the voice is talking so fast that most (sane) people cannot hear it?

 

[Tristicus]

All of the recorders I had went pretty fast. I'd imagine unless your churchgoers are chipmunks, they'd notice.

Newer designs have the ability to time compress - shorten the duration without changing the pitch. This is done in TV commercials too particularly with the small print section. You know the voice is talking so fast that most (sane) people cannot hear it?

I'm insane?

 

[Tiamat]

All of the recorders I had went pretty fast. I'd imagine unless your churchgoers are chipmunks, they'd notice.

Newer designs have the ability to time compress - shorten the duration without changing the pitch. This is done in TV commercials too particularly with the small print section. You know the voice is talking so fast that most (sane) people cannot hear it?

I think, generally, when people borrow the tapes, they are not even considering the fidelity of the recording, but what "message" they missed from the service; so they very easily overlook any sort of flaw with the recording, including a somewhat chipmunk sermon.

 

[Rubycon]

I'm insane?

Ok probably should re-phrase that. Yes you could hear it.

I wish I had a place to host audio files. I have racks of equipment and synthesizers that I could use to demo things.

I think, generally, when people borrow the tapes, they are not even considering the fidelity of the recording, but what "message" they missed from the service; so they very easily overlook any sort of flaw with the recording, including a somewhat chipmunk sermon.

Not to threadjack this into a religious debate but the last time I went I fell asleep.

 

[Jjoshua2]

So I edited my original post. I know some programs can raise the pitch without shortening the length of the recording, and that is what I want to do if possible (which I know it is