Assuming you recorded the audio when he sang to the boom box, load the video with its audio track, then load the studio track below the video’s audio track and simply line up the waveforms. Look for significant drum hits or something that stands out. If they are indeed the exact same audio files you may just be able to line the up beginning to end. If you have some drift towards the end, due to speed differences, you may be able to get away with doing a control drag to shorten or lengthen the audio track to match.
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My Hardware:
Core i7 2.67GHz; Nvidia GTX580, 12 gig RAM Win7 64bit.
My Software:
Vegas Pro V11 with Boris Continuum Complete 7, VASST Ultimate S; Bluff Titler; AE5; PhotoPaint and other stuff.