When reducing noise from a recording simply containing (close-miked) speech, I can’t seem to find a noise reduction setting which will allow for a smooth transition from the “silence” to the “speech”.
IOW, the speech enters again very obviously - with a noticeable increase in gain before it plays.
Is there any way I can adjust things so that this transition is barely noticeable?
If the noise level is particularly high, you will not be able to get a smooth transition. The noise removal effect is for removing low level, constant, background noise, such as tape hiss, or low level background hum.
There are a number of techniques that may help, such as using the Equalization effect to reduce very low or very high frequencies before using the noise removal effect. Also, if you make a copy of the “silent” (noise only) part, but reduce the level using the “Amplify” effect before creating the noise profile, then the amount of noise reduction will be less, but it should be smoother.