Ruben's descent towards total hearing loss is rapid and by the end of act 1 Lou has convinced him to reside at a retreat for deaf people - where we presume Lou hopes he will be able to either learn sign language and / or come to understand what is happening to him. What follows is a treatment of a subject and a community that is seldom seen on film, that subject being deafness. Given the history of silent cinema it may seem strange the subject doesn't get wider treatment, but even silent cinema isn't really silent. The 'silent' cinema of the 1920s was accompanied by a piano player after all. When Buffy the Vampire Slayer did a 'silent' episode it was only the characters who were silenced, the sound effects and musical cues are alive and well. A true treatise on a descent into deafness suffers from the same issues that all 1st-person film-making does; it's just really hard to make a film from the 1st person. How to tell a story about deafness and silence through the medium of film, a medium so reliant on sound? Well that's what Sound of Metal does. And it does it well enough to be recently awarded the Oscar for Best Sound. Creating dead silence and engaging discordance is a lot LOT harder than you might think.
But Sound of Metal is really about addiction. Yes it's about the literal addiction that Ruben has suffered and the crutch that music and Lou are to him. But it's also about the less literal addiction that we each have to our own way of life and our ability to sense the world. When Ruben is told he has to leave loud noise behind, he can't do it. When he is offered a choice between hard work and an expensive quick fix, the fix is his new addiction. Ruben's only kicked his addiction because he was able to focus on Lou and the music. So the loss of the music terrifies him, but how much is the music an addiction in itself? How to live without something you've always known? It's a terrifying prospect.
When I started watching the film I was expecting music to be the saviour. But the title has a double meaning; at first it's Ruben's saviour, later a grating cacophony keeping him from changing and growing. The film almost ends where it starts, with Ruben fixated on something and trying to keep his addiction at bay. Great performances from Ahmed and the supporting cast, and a superb treatment of a delicate and scary subject. Definitely worth 2 hours of anyone's time.