Music From the Inside Out is a documentary that explores the question, "What is music?" Filmmaker Daniel Anker spends 90 beautiful minutes with members of the Philadelphia Orchestra, seeking the answer to that question. As Israeli cellist Udi Bar-David comments in the film, "This is a lifetime challenge… you want a brief answer — you expect a brief answer?" There is no short answer to describe music, and even after watching the film, one is left with a sense that there is still more to be explored. Ankler breaks the question down into three interwoven parts: "Finding a Voice," "Between the Notes," and "The Sum of the Parts."

In the first segment, the musicians describe what compelled them to perform music, and orchestral music in particular. Cor anglais player Elizabeth Starr Masoudnia says that she was drawn to music "partly because [she] wasn't very articulate with words." This concept of music as self-expression beyond spoken language is shared by many of the other participants in the documentary. Another aspect of the musician's voice is his or her individual interests and contributions to the whole, which creates the distinct performances of standard orchestral pieces and set them apart from wooden reproductions of the same. As trombonist Eric Carlson notes, "You can't define great musicianship, but you know it when you hear it."

The second segment explores the space between the notes where music is created. Silence between the notes creates anticipation and heightened awareness of the notes themselves. As spoken language uses silence or pauses to convey meaning or emphasize particular words, so does music. The idea of music as language and storytelling is brought up again in this segment. Principal timpanist Don Liuzzi states that, "a great piece of music tells a story. It doesn't have to be a literal story, but a story of ideas and the connection of ideas." Not any random collection of sounds is music, according to principal second violinist Kimberly Fisher. She notes that the "difference between noise and music is the organization of it and the intent of it." Music becomes music when it follows a structure, no matter how loose, that allow the performer and the listener to find meaning in the notes.

The third and final segment reiterates the concepts presented in the first two and brings them together in an attempt to explain the organic nature of music. Like language, music can be picked apart in to its discrete components and analyzed, both figuratively and literally, but each of those parts are meaningless until they become part of the whole. Once again, Bar-David expresses this beautifully: "The ideal performance is when you don't know your name; you don't know what piece you are performing; you don't know who is standing in front; you don't know who is behind you. There is just one great sense of being, where one thing leads to another."