perk up one's ears

To perk up one's ears is to suddenly become attentive or interested, like a dog or cat whose ears physically rise when they hear something intriguing.

The expression describes that moment when something catches your attention and you start listening more carefully.

She perked up her ears when she heard her name mentioned in the next room.

The phrase can describe literal alertness or figurative interest in gossip, opportunity, or any potentially relevant information.