Wave files that sound like chipmunks!

Of course I'm perplexed. A customer brought me some mono tracks of his wedding's audio events. They were apparently recorded with high-end gear as the chipmumks sound superb but I can't mix-down something that sounds like 3 3/4 ips tape played at 7 1/2 and have a happy customer. I have SoundForge but haven't a clue about how to use any of it's functionality to slow the files down to normal speed so I can mix the tracks. Any ideas as to what to try next?

Thanks in advance and forever after!

I did try resampling at 44,100 through Sound Forge but SF said the sample rate was already at 44k so it couldn't happen. I have a soundcard that's capable of 96 but don't know how to set it up.

Thanks Mark.
I do have the originals on CD so I can play with impunity. How does one set the sample rate. (I use Sonar - not HS but I would have to think that the functionality is close to the same in either app. If I R-Mouse click on the track and "Import Audio", my only choices are "Mono or Stereo" and "Copy to Project Folder". Don't see anything in regards to sampling rate.

I really appreciate your helping on this.

Since I've been doing alot of this lately I even know the answer: When you import the file in Sonar, on the lower left of the import box it will tell you the sample and bitrate of the file you've chosen. Because of the ideosyncracis of my MOTU 896hd, I have to make sure that the driver is set to the same rate as the file I am inputing in the driver control panel. (hard to know what this might be on a file you don't know beforehand but the MOTU has no AUTORATE setting) I get to close the program and reset the MOTU accordingly.

You should be able to set this in options- audio within Sonar. If it doesn't seem to take, find what the file is in the import screen, close the program, set the samplerate and bitrate in you cards control panel, open Sonar, reimport. It should work

Sonar will export the file to whichever sample and bitrate you choose regardless of how the card is set.

My wave files still have chip noise.
 
I loaded audocity and saved the files again with
the best sound.
 
No help.  The original files are 16 bit 44.1khz.  They came from a tascam
recorder.
 
My best guess is my sonar is loaded on an Acer laptop and the sound card
is only a 16 bit card.
 
Any work around would be cool for now.
 
Paul

Thanks for your reply.
I have sonar x2 studio.
Yes I do need to upgrade my computer.
The built in sound card on this laptop is weak.
Paul