Here's an excerpt from an interview by Stathis Gourgouris:

I grew up with classical music in my parents' house and with pop music. There was no experience of contemporary music otherwise […] But pop music was my most important influence after classical music. And my first way of liberating myself from teachers who taught me the classical repertoire was to play songs that I heard on the radio, songs of the Beatles, the Beach Boys. [1]

There is already plenty of material in this excerpt. Let's focus on this: he knew Euro-classical music because he studied it on the piano. He played – or tried to play – that music during his formal training, reading scores, while popular music came into his life as recorded music through the radio. Here are two substantially different ways of music consumption – scores and recorded music. [2]

During his teenage years he also played in a group:

Later on, I had a band and we played Eric Burden [sic], Jimi Hendrix pieces, whatever. But this is how I learned a certain freedom, primarily in the way of performance, non-conducted performance, and definitely the freedom in creating music together as a group, which is really the most important thing about rock music. I mean, what is Paul McCartney without John Lennon? Even if John Lennon didn't write as much, even if they didn't actually write everything together or equally every part, etc., it is by the very discussions they had about the material, by the encounter itself, that the great pieces happened. The encounter was the creative instance. No one was ever, truly, working alone. [3]

The attention to creative collaboration is clear throughout his whole life, and we will focus on some examples, but let's indulge a bit more on the concept of collaboration and the meaning Goebbels gave to it while joining the Sogenanntes Linksradikales Blasorchester.

It is here [referring to the SLB] that I also learned about collective judgment in relation to various commitments, to decisions about where to perform, or what to perform, how to learn a piece, how to compose it, etc. - you know, collective judgment in musical terms in the widest sense-which was very helpful and constructive. I never considered these decisions to get in the way of my aesthetic point of view. I found it a very helpful experience to accept that, as a composer, you don't have to be alone in your room. It was very important for me. [4]

In his mid-20s, while discovering the figure of Hanns Eisler and the possibilities of using politics into music as a compositional tool, Goebbels found his way through composition as a practice, as in the definition by Christopher Small of musicking, that is, the practice of music [5]. In this case, composition is a shared practice to be done along with those who are meant to play that music.

With these three citations, we already have three key-concepts to understand Goebbels' music: recorded music, non-conducted performances and collaboration.

As we can see in Figure 1, Goebbels worked in bands – that is, as a popular music musician – until the 1980s, but his approach to composition – or, should we say, to musical direction – didn't change that much.