Audio quality deteriorates on Rendering I have a video from which I extracted audio to clean it using Audacity. I applied both High Pass Filter (50 Hz) and Low Pass Filter (1000 Hz)  and then used Noise Gate to remove unwarranted noise.

Now, when I merge the audio back with the video, it plays fine in the Editor (I have tried several paid and free programs), but after rendering, the audio quality becomes very poor with constant random noise in background.

What may be the cause of it? Any idea?

Edit -  I found out that the rest of the audio stays almost the same, but the voice's texture changes to be a lot noisy. I am sure I'm doing something wrong, but cannot point out what.
The audio is clipping internally somewhere from the sound of it.  The background noise gets louder and so does the speaking, but the speaking is getting crushed.  I'd double check if there are any adjustments being applied in the render.  It sounds like either an incorrectly adjusted limiter or possibly an additional signal boost being applied.  It might also be rendering in to a lower bit depth that clips.