Hi,
 
When I finish a song and want to render it down to an MP3, about a third of the time I hear a little quick noise at the very beginning of the finished track. Maybe I'm doing something wrong?
 
Here's my method:
 
1. Finish song
2. Highlight all the tracks
3. Hit File>Export>Audio
4. This opens a new folder window where I select "MP3"
5. I name the song, add artist name, etc.
6. There are lots of buttons on this screen and I leave them all checked, such as enable fast bounce, etc
7. Click "Export" and it renders the file
8. Play it back and 2/3 of the time it sounds fine but about 1 out of 3 there is a very loud little noise at the very beginning that lasts only a nano-second but it is definitely there.
 
My dithering is set to triangular, rate is 41,000, 16 bit
I use an Apollo Twin Quad with Thunderbolt 3.
 
Should I change anything?
 

Clear your buffer first? Idk. I don't have this problem, but it is a thought. Play your project in a place with no audio before exporting and see if it is still there.

My first thought was the same as Geoff's - you may be hearing some leftover data from a previous playback. One way to be certain to avoid that is to do your export after opening the project, without playing it first (after waiting long enough to make sure any sample libraries get loaded, of course). Or, you can simply initiate playback for a second or two, or however much silence you have at the beginning of your song. Stop playback before it gets to the actual data. That'll flush any lingering reverb tails.

My take on this is you are missing an important step by directly exporting a multi track song to a MP3.... it's called Mastering. 

I kinda do master it with Ozone 8. Everything is funneled to it. And yes, I think it's some sort of reverb tale or similar. 
 
More info:
 
I typically send all vocals to one sub that has Waves vocal-rider, another sub has all instruments (with send to vocal-rider), another sub for reverb and another for delay, all of these are directed to the Master sub where I have Ozone 8 Advanced. Sometimes I'll add another sub for Anteras Harmony engine.

bitflipper
...simply initiate playback for a second or two, or however much silence you have at the beginning of your song. Stop playback before it gets to the actual data. That'll flush any lingering reverb tails.

 
I used to do that often. It seemed to be necessary whenever doing a second export immediately after just completing one. Apparently the buffers were not getting flushed out after an export as they normally would after a playback. But since changing my interface from a Line6 to an Audient, it has not been a problem.

Bitflipper is correct, and all you have to do is edit the wav that you created via the bounce. It's happened to me since Home Studio 2004.

If this is a fading reverb tail then you might benefit from extending the length of any clip at the end of your project so that the increased length picks up everything

Hi. I've had this happen when a sound hadn't released properly. In those cases, I press play a second and stop again.
That usually cures it for me. It doesn't happen on a regular basis, so I haven't gotten to the cause of the problem.
All the best.

Thanx for all the suggestions. I tried toggling the big FX button before exporting and that seems to help as well.