I have exported the file to Mp3
First problem. Never do production in MP3. The process of making an MP3 creates sound damage and makes filters, effects and tools more difficult to use. Export everything in WAV until you get to the point where you want to upload a show or put the work on your iPod. Then use the MP3.
There is white noise when there is no vocal speech.
Actually, it’s there all the time but it’s more obvious when people stop talking.
Noise Reduction, but don’t bet the farm on it working well.
Noise Reduction works in two steps. You expose Noise Reduction to a sample of the evil sound, say for example, a ventilation fan whine. It needs to be the fan noise absolutely by itself. That becomes The Profile. You launch the tool again and apply it to the show and Noise Reduction will try to subtract that exact ventilation fan noise – the Profile – from the show. So far so good. You can imagine those steps without too much trouble.
When you make a Profile from a sample of tape hiss, Noise Reduction gets a profile of “All Sound.” I’m not making that up. White Noise has tiny samples of every sound you can hear. When you apply Noise Reduction to the show, Noise Reduction will try to remove – the whole show. Obviously that’s not optimal, so there are tricks you can try. Frequency Smoothing is a setting that causes Noise Reduction to “go around” spoken words and doesn’t try to do anything to them. If you have a simple, well behaved show, sometimes that’s enough. If you have severe hiss, this process will give you hissy words over a quiet background. It turns everybody into snakes. If you have a complex, highly produced show, it doesn’t work at all.
It helps to avoid the idea you’re going to turn this into a studio production. That’s not going to happen. Start with modest noise reduction values like 6 dB or 12 dB and work up. Each time you increase the reduction, listen for the hiss reduction, but more important, make sure nothing bad happens to the voices. You are looking for honky, bubbling, gargling, fading voices like a bad cellphone call. That’s what it sounds like when you apply too much Noise Reduction.
Nobody will be surprised if all you can do is gently reduce the hiss and still leave the voice performance in pretty good shape. Like earlier, it’s never going to be Glen Glenn Sound Studios. Recovering from hiss is very difficult.