Lateral lines are the ones that fish depend on most to detect noise created by nearby schools of baitfish or other tasty morsels, like a crayfish or worm. In combination, the otoliths, the swim bladder and the lateral lines allow fish the ability to hear even slight displacements of water from several feet to even miles away. They can hear a nightcrawler wiggle, a leech swim and the struggle of a wounded minnow. Like us, they can measure whether sound is getting louder or softer, so they know if prey is coming closer or going away. Individual, smaller fish have a stealth advantage over bigger fish.
Little ones disturb less water as they swim so they make less noise.
But, the racket caused by schools of baitfish is cumulative. Studies have revealed that individuals of some species know when a meal is close. This is because they can identify the noise that others of their kind make as they feed. Not much when fish are finicky and water is clear. Testing and experience on the water have discovered several ways to add sound to a variety of livebait presentations and lures.