First, a couple of small corrections: Neither "evidence" nor "testimony" requires an article before it. One doesn't acquire occurrences [note the spelling: two r's]; an occurrence is simply an event. And while it's "evidence of," it's "testimony to."
In my observation, song lyrics are often testimony to life experiences. (The "acquired" isn't really necessary; if you're singing about your life experiences, or your songs are testimony to them, it's understood that those experiences have been acquired by you.)
If you want to say, rather, that the lyrics are evidence of the singer's life experiences, probably "reflect" would be better than "are evidence of." Just a suggestion.