Primal Roar
Your eidolon unleashes a primal roar or other such terrifying noise that fits your eidolon's form. Your eidolon attempts Intimidation checks to Demoralize each enemy that can hear the roar; these Demoralize attempts don't take any penalty for not sharing a language.
Traits
Auditory actions and effects rely on sound. An action with the auditory trait can be successfully performed only if the creature using the action can speak or otherwise produce the required sounds. A spell or effect with the auditory trait has its effect only if the target can hear it. This applies only to sound-based parts of the effect, as determined by the GM. This is different from a sonic effect, which still affects targets who can't hear it (such as deaf targets) as long as the effect itself makes sound.
A creature with this trait is a summoner's eidolon. An item with this trait can be worn by an eidolon. An eidolon can have up to two items invested.