Transcribing your audio can help to increase the audience that discover your content. People learn in different ways - some read, some listen and others watch. YouTube allows you to upload your own transcription documents and will sync the writing perfectly with any video. You can also click to have your transcription translated into different languages. Look at your statistics and check to see if you have viewers or listeners in different countries. Translating audio transcriptions can help you to reach a whole new language.

My Adobe Audition Tutorial (with multiple language captions): http://youtu.be/hlKzx7ol_-o
YouTube Caption Translation: http://youtubecreator.blogspot.co.uk/2013/02/get-your-youtube-video-captions.html