Executes the skill when the mob hears a sound, [if this feature has been enabled](/Mobs/Mobs#hearing).
The `<skill.var.volume>`[placeholder](/Skills/Placeholders#variable-placeholders) can be used in the triggered skill to return a float value between 1 and 15 representing the distance from the sound source
> The associated [@trigger](/Skills/Targeters/Trigger) is the entity that generated the sound
> The associated [@origin](/Skills/Targeters/Origin) is the location where the sound was generated