Insert the video file whose audio you'd like to adjust into your Final Cut Pro 7 sequence.
Click on the clip in your sequence so that it is highlighted.
Choose "File," then "Send To" and then "Soundtrack Pro Audio File Project." Soundtrack Pro will open the audio file of your clip.
Select a portion of the audio waveform that contains the noise you would like to reduce from the entire file. To do so, click and drag your mouse to highlight this portion of noise.
Choose "Process," then "Noise Reduction" and "Set Noise Print."
Highlight the entire portion of the audio file where you would like noise reduced. If you would like noise reduced from the entire audio track, use the keyboard to select Command+A to select the entire file.
Choose "Process," then "Noise Reduction" and "Reduce Noise." The Reduce Noise options box will pop up.
Adjust the threshold, reduction and tone control of the audio file until you have created a sound to your liking.
Click "Apply" in the Reduce Noise box.
Export your new sound file as a .aif file.
Go back to your Final Cut Pro 7 project file.
Select "File," then "Import" and "Files" and import your new .aif sound file.
Insert your new audio file and delete the original audio file.