Leighton Trent’s review published on Letterboxd:
About twelve years ago I watched my mother very rapidly go from being partially blind, which she had been for almost sixty years, to being competely blind in the span of just a few months. Watching Riz Ahmed portray the grief of a loss of something that is so vital to our humanity brought me back to my mother's fits of crying and anger during that time of her vision loss. She could not accept that her own body and time itself were against her. She sought help, sought tools, but never sought to better herself afterwards. That the film ends up showing Ruben's acceptance of his loss is something she could never do. She retreated within herself, fighting tooth and nail with only futility to follow, but never accepting herself for who she had become. She always saw herself as handicapped, as the victim, and Ahmed's Ruben eventually is able to see past this, realizing that there is nothing that can make it like the way it was before.
Because of my mom, I was immediately pulled into this headlong. This kind of authenticity on film is rare, but what makes Sound of Metal work so well. The character work is painted in fine strokes, most especially between Ruben and his girlfriend Lou (played wonderfully by Olivia Cooke), whose relationship is shown through the dichotomous lense of the before and after of Ruben's hearing loss, but also with Paul Raci's "Joe" who runs a deaf program out of his own house that Ruben begrudgingly accepts help from (and whom Joe seems to see a great deal of himself in Ruben). The emotions here, much like music, build and build and build until they explode in Joe's last scene with Ruben, and even Lou's. This is simple but strong writing; the emotional pain is acutely felt and ultimately satisfying for where Ruben's emotional journey concludes.
And I could probably write a couple thousand words about the extraordinary sound design here - which can be such an important and often overlooked storytelling tool - that provides a complex audible journey for our main character. Without it, the film loses so much of the muscle that makes it one of the best of 2020.