[Karlos Bena]

I see your post is dated August 2014 and here we are August of 2016 and this problem still persists in the Premiere Pro software. But good news!!! I figured out a workaround. Ok, so there are a few seconds that the Denoiser effect needs to be able to initiate so if you have cuts that are edited and you apply the effect to each one, you will still get the hiss for the first few seconds on each clip upon export. When you are editing it sounds fine but when you export you can hear the hiss. Not cool right?
So, what you do is apply the effect to the master clip before editing. Hopefully there is some lead time (at least 5 or 6 seconds) at the beginning of the clip before your audio starts. Export just the audio into a wav file to your media folder. Then import the wav to your project. When you play the clip it will have the hiss at the beginning but then it will stop after a few seconds and the rest of the clip will be hiss free as there is no effect on this clip. Then you can edit the clip into many sub-clips and there is no more problem. I just did this with a narration audio clip and it worked fine. I guess the only problem will be if you do this workaround on a video/audio clip, you will have to export both the audio and video and that will take longer. Otherwise you will have to separate the video and audio files and then sync them up again in the timeline after the workaround. Kinda sucks cuz it’s a lot more work and can get complicated with all the extra files but it works. i hope this helps you or anyone else reading this post.