There is a scene of relatable terror early on in director Darius Marder’s Sound Of Metal that will hit hard with any fan or performer of heavy music. Ruben Stone, drummer with avant-garde noise rockers Blackgammon – a squalling two-piece completed by guitarist/vocalist/girlfriend Lou Berger – is bullshitting with a promoter and venue staff as he sets up the merch table for the latest show in a tour through America’s Midwest. Vinyls are neatly laid out. The price of a “custom” spray-painted T‑shirt is playfully debated. Then, all of a sudden, the wittering background noise drops away into bruised semi-silence. Hearing-loss, an agonisingly concerned specialist subsequently explains, can be abrupt and irreversible. The only course of action to be taken, aside fr...