The heartbeat is one of the most widely recognised sound effects in film, television and online video because it needs no explanation. Editors have long used a recorded lub-dub pulse to signal fear, excitement, love or physical strain, and the same effect has become a staple on soundboards and in short-form edits where a few seconds must set the mood instantly. Its popularity endures because listeners respond to it physically, making it useful for horror, romance, drama, fitness and medical-themed content alike.