On what computer operating system are you running Premiere Elements 9? And, please install the 9.0.1 Update if you have not already.
Are you wanting to sync the audio to a video file from which its audio has been removed?
If so, right click the Timeline video, and, from the pop up menu, select Delete Audio.
Then import your .mp3 files to an audio file, and align them with the video file on the video track.
For fine adjustments, as you hold down the Alt key of the computer main keyboard, tap the left or right arrow key once. One tap = nudge of one frame.
Or, as you hold down the Shift+Alt key of the computer main keyboard, tap the left or right arrow key once. One tap = nudge of 5 frames.
Consider: Edit Menu/Project Settings/General and setting Display Format = Milliseconds.
Please review. Any questions or need clarification, please do not hesitate to ask.
I have a Macbook Pro (pre Retina) running the latest OSX 10.9.5
9.0.1 update has been installed.
I am a novice. So, I took video from my Sony A7 which has a microphone built in for purposes of syncing with the actual good audio track taken from an external recorder using two XLR mics. So, the video does have its own audio. I Have not removed it.
Your answer is very good. Thanks. The problem I am seeing is that even with handclaps or other syncing starts, the video camera may have to be turned off or paused and not have the audio recorder follow suit exactly. So, syncing audio to the start of the whole video is needed but not sufficient to handle the interim starts and stops.
Also, what sampling rate do you recommend for the audio in the external recorder to ensure that there are no glitches?
For best sampling rate for your external recorder, I would probably go with 48 kHz if CD is not involved.
But, best check out the online articles that speak to the 32, 44.1, and 48 kHz sampling rate considerations.
I would not go overboard on the audio bitrate.
Are you using the technique of trying to sync the clapping of hands spike in audio display (external recorder) with the clapping of hands spike in the audio display which is linked to the video?