“…9 However, the technical challenges in using ultrasound waves for nonlethal attacks include the rapid absorption of ultrasound by surrounding air and a requirement for close proximity to the source to induce injury. 7 In any case, the analogy to concussion may be unnecessary as many of the symptoms described also occur in other medical, neurological, or psychiatric conditions. In particular, persistent postural-perceptual dizziness (PPPD) is a syndrome characterized primarily by chronic symptoms of dizziness and perceived unsteadiness, often triggered by acute or chronic vestibular disease, neurological or medical illness, or psychological distress.…”