Sound of Metal has really good internal logic. It has to. A musician is going deaf, the film is mostly from his perspective, it can’t make the audience go slowly deaf (without breaking a myriad of laws) – so, it has to have really good internal logic. 

It does this via diegetic sounds. I mentioned this term before, but for those of you unfamiliar with it, diegetic effectively refers to in-universe sounds. During a film, if the camera was your own point-of-view, could you hear the sounds? If yes (an alarm buzzing, phone ringing, record playing), it’s diegetic. If not (orchestral scores, character narration, a lightbulb pinging to imply a eureka moment), it’s non-diegetic. 

Throughout the first 15 minutes of the movie, you’d be hard-pressed to find a non-diegetic sound. That tinnitus effect we heard before comes closest in the first scene – we just saw the drummer protagonist, so is it what Riz Ahmed’s hearing? Is it a collective experience caused by the loud concert? Who knows, and that doesn’t matter – the audience can hear it. 

Following on, we hear a bunch of distinctive sound effects that highlight actions on-scene. Coffee-dripping, blending up a smoothie, clothes rustling during a workout. They’re super prominent, elevated above the background ambience, and finely detailed to an almost-ASMR level of quality. This location and these actions then repeat several minutes later, after a re-introduction of the tinnitus SFX. Now they’re muffled, completely distorted, and almost indecipherable. Physically, these objects should still make the same sound as before, but because the drummer we’re following is going deaf, they aren’t. The internal logic is entirely upheld, sealing his probable fate with a damningly oppressive sound effect. 

This idea of internal logic is perhaps most prominent during the pharmacy and doctor scenes, which end our 15 minute examination. The film breaks two laws of physics: 

  • A chemist’s handwriting is even remotely legible. 
  • A doctor’s handwriting is even slightly comprehensible. 

Jokes aside, these scenes flick between the perspective of Ruben, our protagonist, and the specialists he’s seeing. When we’re in Ruben’s sound perspective, everything is muffled. When we’re outside of his shoes, everything is normal. This meticulous internal logic is reinforced by the cinematography and upheld throughout the movie, so that whenever it breaks, it’s impactful and there for a reason.