You're likely recording with a mono rather than stereo microphone.
Not a big deal. You can just apply the Fill Right audio effect to your narration and it will fill both channels.
A good mic for narration will be mono, and have a hyper-cardioid pickup pattern. This will greatly reject off-axis sound, like the fans in your computer's case.
As Steve points out, one can Fill-Left, or Fill-Right to get 2-channel Audio. It is not stereo, but 2-channel mono. As I do a lot of DD 5.1 SS, I "locate" my narration in the Center channel, and then often feed a bit of it into the Ls, and Rs channels with a bit of Delay and Reverb for some depth.
Thanks for the response. I'm not sure how I "fill left" and "fill right".
I'm also not sure what Steve meant when he said "I 'locate' my narration in the Center channel, and then often feed a bit of it into the Ls, and Rs channels" What is the Center Channel?
Actually, that was Hunt. Not me.
But apply Fill Left (or Fill Right) is as simple as locating the effect in the program's audio effects and dragging it onto your narration clip.
You do know how to apply an effect, right?
Unlike my ability to write the correct name in my post (sorry Steve), I do know how to apply an effect. I hadn't realised it was that easy. I was looking in all the menu options, trying to mix audio, searching in preferences etc.
Thanks for the assistance. It's definitely fixed my problem.
In my case, I am almost always working in DD 5.1 SS in PrPro, and then doing my Audio Export through the Minnetonka Audio SurCode DD 5.1 SS plug-in (optional in PrPro only) to AC3 Audio. With that, I can locate my narration where ever I want in the Audio "stage." For the narration track, I locate most of the source to my Center channel (with DD 5.1 SS, one has L (front), R (front), Center, Ls (rear), Rs (rear) and LFE) with just a touch of it going to the Ls & Rs channels, usually with a hint of Delay Effect and Reverb Effect applied.
For narration, I always use a mono source from a hyper-cardiod (pickup pattern type) mic. This allows for two things: the pickup concentrates on the voice of the speaker and rejects ambient sounds and all off-axis sounds, and allows me the ability to pin-point the source.
With a stereo mic, the pickup patteren is spread more, and picks up more ambient signals, and then in the mix spreads the speaker's voice around the sound stage. I feel that narration should sound as though it's coming from a tightly defined source. The use of the Ls and Rs is only to expand the depth of the narration, as though the speaker was actually on the same "stage" as the performers/subjects, i.e. to mimmick room acoustics a bit. If the scene is taking place in a large auditorium, and I want it to sound like the narrator is actually there, I'll feed more signal to the Ls and Rs and add more Delay and Reverb. If I want the speaker to be totally detached from the action on screen, then I'll use the Center channel only. It depends on what I wish to accomplish.
Sorry that I was not clear in my response.
Looks like Steve has gotten you to the right spot to apply the Fill Left/Fill Right Audio Effects. If not, let us know and we'll point you to the right place.