As we know, bass attack prey by sight, smell, sound and vibrations. When a bass can't see it's prey, the ability to detect sounds and vibrations become a necessity for survival. Water transmits sound five times greater than at sea level(1500 meters/sec). All types of prey emit some type of sound such as clicks, pings and rubs. I doubt many artificial manufactured sounds come close to "natural" pitches and tones produced by prey; however, a number of these manufactured rattles do attract bass to our lures.

Rattling sounds (volume and pitch) emitted by crankbaits depend upon the chanber's shape, volume, thickness and composition, as well as the size and composition of the ball rattle. Flat baits produce louder, more intense sounds. Round baits produce softer, more muted sounds. Large, deep diving high-volume baits may be overkill. Rattling sounds in soft plastics are made of glass, plastic and metal and are housed in an array of plastic and metal chambers, but most end up as tinny jingles.

How you fish your lure will also afftect the rattle's rhythm. A constant retrieve will produce a constant rattle; others, only rattle when you twitch your rod tip. What works is what bass want on any given day. Rattles are most affective when bass have limited vision conditions such as stained water, dense weeds, warm water discharge (air bubbles, current noise) and deep clear water.

Pesonally, I hate loosing my rattle-stuffed baits to a two inch bluegill, rock bass or warmouth on steroids so I place either glass or plastic beads above and/or below the weight when using a T-rig or C-rig. I think the glass bead imitates a craw a little better than the lower tone of the plastic bead. Anyway, I think much more research needs to be done to produce lures that make a more natural sound.