Whistle of Silence (5e Equipment)

Wondrous item, common

When you blow this magic whistle, you designate any number of creatures you have seen at least once and only those creatures can hear the sound. You can designate a creature you haven't seen in person if you have seen an accurate depiction of that creature, such as via a spell or portrait.
For a creature you didn't designate to hear the whistle, it must succeed on a Wisdom (Perception) check contested against your Charisma (Deception) check.