After getting home and going through the footage and audio in a much more quiet environment, I did notice that there was still some noise from the air conditioning unit being picked up on my recorder. To get rid of this I went into Audacity and carried out several passes of noise reduction, each time recalibrating the sensitivity as well as the expected noise profile. This proved to work really well and when put against music there is no evidence of background noise and the speech is left sounding untouched. Although it was easy to remove, it did slow my process down a bit so I will have to take much more rigorous measures for future interviews to eliminate sources of noise before recording.