Julian Johnson, Regius Chair of Music at Royal Holloway, University of London, writes about this scene:

Anyone who knows The Shawhank Redemption will recall the effect of this iconic moment, when the prisoner, Andy Dufresne, locks himself in the prison office and plays a duet from Mozart’s opera The Marriage of Figaro over the PA system. The entire compound comes to a standstill as the strains of the music drift over the exercise yard and hardened prisoners and guards alike stand open-mouthed, silenced by the arresting beauty of a music from a distant place.

Nothing could sum up better what I have tried to say in this book.

Of course, you might think, any music would have done; music, as a whole, has this capacity to make the imaginary seem palpable, to promise something that exceeds our immediate reality, to recollect the loss of something infinitely valuable.

But I think it’s significant that the director, Frank Darabont, chose to use Mozart at this moment. The disjunction between the world of classical opera and the brutality of the prison in which the film is set, its very strangeness, is the key to its power to stop “every last man” in its tracks. Part of its beauty, and the incomprehensible power of its fragility, derives from this sense of distance—that this music comes from elsewhere and speaks of a better order of things that, for this brief moment, cuts through the hardened surface of everyday reality at Shawshank.

The sense is enhanced by the effect of hearing music from an old vinyl record, played through the tinny speakers of the prison PA system, whose normal function is one of repressive control. The hiss and whirr of the record, the distortion of the speakers, combine to create the effect of a music heard from a great distance, not just in place but also in time. The beauty of these voices, it seems, is brought into the present from another age, as an ephemeral restoration of something lost of the past. For “every last man” this music sounds from a quite different world, yet it enters the mind like a distant, long-forgotten memory and the most fragile of future promises. Allowing it to sound through the bars of this “drab little cage” is a deeply transgressive act, for which Dufresne gets two weeks in solitary confinement, and no doubt a beating too.

Professor Johnson wrote this in the preface to the paperback edition of Who Needs Classical Music? Cultural Choice and Musical Value (Oxford University Press, 2002), xi-xii. He goes on to state the concern, question, and proposal he offers in the first edition of his book:

My sole concern was to restate the claims of classical music for a contemporary world in which they seem to have become almost inaudible.

My question was how classical music might still have a distinctive value in the twenty-first century.

My answer was to suggest that, at its best, this music involves us in tracing out patterns of thought, feeling, and experience that relate to some of our highest ideals as human beings.