can we render only audio in blender? I want to cut a portion of audio file and render in mp3 or aac, but in render tab i can not find any settings for this. i also went through this thread:
http://blenderartists.org/forum/showthread.php?247012-Render-Audio-Only-in-Blender

But i can not see any button called "mixdown" in the scene tab. I am using version 2.74. so is it possible to render only audio?
Yes! You have to go to the render panel, then under the render panel and click on the audio icon (next to render and animation). 



Then you can choose different audio outputs and settings (on the left at the bottom of the screen under the tab mixdown). 



And then you push the button mixdown (at the top right).