"Amidst the record's scowling noise and swarming totality, the consistent knock, pitter-patter, or clash of Shane Maguire's drums keep listeners tethered to some semblance of reality, while Ball's ethereal voice enacts as the beckoning guiding light that airlifts listeners from the disorienting void they've been thrown into. Even when she utters lines like "Lost for a second/In the silence that's staring back" on "Mirrors" (...), Ball's voice emerges from her own pit of chest-tightening anxieties to be redemptive daybreak. It's easy to get sucked into darkness and despair, 'Heart Under' proves that so, but thankfully, Ball's voice oversees that listeners only merely toe into these bottomless, murky waters".