"Heh heh heh... I knew you were coming ten minutes ago. This thing in my ear is a Galactic Receiver. With it, I can hear an ant burp a mile away! ...Actually, I was snacking in the cafeteria when I heard your footsteps, so I hurried back here!"
The Galactic Receiver is a ear-like headset that Jaco wears.
The Galactic Receiver is a special device that Galactic Patrolman Jaco wears over his ears, granting him enhanced hearing capabilities. According to Jaco, it can allow him to hear an ant burp from more than 300 feet (a mile in Xenoverse 2) away. Ironically, due to its appearance it can be easily mistaken for being Jaco's actual ears as Goten and Trunks did when they first meet Jaco in Dragon Ball Super when Goten accidentally removed the receiver on his left ear and became horrified thinking that he had accidentally torn off Jaco's ear, only for Jaco to reveal it to be a communication device.
Video Game Appearances
"A state-of-the-art Galactic Patrolman radio. Often mistaken for ears."
— Dragon Ball Xenoverse 2 Accessory description
In Dragon Ball Xenoverse 2, Galactic Receiver appears as an accessory under the name Jaco's State-of-the-Art Radio which can be obtained by the Future Warrior (Xenoverse 2) as a reward in Parallel Quest 72: "First Training". Like most accessories, it is purely cosmetic and has no effect on the wearer's stats.
While training under Jaco as their instructor, he will claim his Galactic Receiver allowed him to hear the Future Warrior coming while he was snacking in cafeteria allowing him to race back to meet the Warrior for training.