This project is a collaboration between the Royal Centre for Defence Medicine, The US DoD Hearing Center of Excellence, The University of Cambridge and University Hospitals Birmingham NHS Foundation Trust. It arose out of concerns raised by service personnel, unit commanders and occupational physicians that people exposed to high velocity weapon systems often seem burdened with hearing problems out of keeping with their pure tone audiogram. The project is using a range of psychophysics and auditory electrophysiology methods to investigate this.