prick up (one's ears)
欹 centers on the action of pricking up one's ears, as when listening intently or straining to hear something.
欹 combines 奇 (unusual, strange) and 欠 (open mouth, lack). The exact historical development is uncertain, but it likely relates to an unusual or tilted posture of the head when listening carefully.
The left side 奇 suggests something unusual, and the right side 欠 looks like a person with an open mouth or tilted head. Imagine someone tilting their head strangely to prick up their ears and catch a faint sound.
For イ, picture an ear (イヤー) pricking up to listen: ear -> イ, and the strange tilted head helps you hear better.
to strain (one's ears, eyes); to prick up (one's ears)