I recorded some audio with an external mic using Audacity. I have this sound throughout the track. What is this? What would have caused this? How do I remove it? This is my first attempt at audio editing, so BE NICE 
Attached a picture of the waveform. Any more info required?
Set the recording input in the Device Toolbar to the external mic (not “Stereo Mix”)
This is a recording already done. I am only starting to edit the recording now.
It seems to be all the information on the Right channel, that is where the noise is. It is also duplicated on the left channel, where the data is that I need to be using. My mind tells me that I just want to remove the data on the right channel, as well as find that same data on the left channel and just remove it. I am sure though that is easier said than done?
If you are really lucky, the “Vocal Remover” effect my do the job (default settings).
If it doesn’t then I think there are no other options other than re-record.
Thank you! It worked like a charm. Help me to understand it though. I assume because there was the exact same pattern on both channels, the application assumed it was vocals? And just removed it? On the right track?
Further, I now have some sound, background noises behind the obvious main sound. Is there a way to automatically cut it all out? To give me pure silence other than the main (loudest) recording?
The Vocal Remover effect is described here: http://manual.audacityteam.org/o/man/vocal_remover.html
Basically what it does is to “invert” (turn upside down) the waveform in one audio channel then add (mix) it with the other channel, thus cancelling out any signals that are identical in both of the original channels.
Try the noise gate effect. It is an optional plug-in: Missing features - Audacity Support
See here for how to install: Missing features - Audacity Support