I'm editing lectures, there is air conditioner noise in the background, I reduce it through the noise reduction effect, but the problem is that it creates a bit of an echo at the end of each sentence.
My question is how do you overcome it? What parameter should be changed in the settings so that this does not happen?
There's a (quite long, but detailed) thread about this here. Best to read the whole thread - it does contain all of our combined experience. Yes it's quite an old thread, but nothing has changed, and the basic advice applies to pretty much any NR you use, including iZotope's.