If bass anglers are not fully agreed on the effectiveness of sound, they agree even less on what sounds work best. To some anglers the louder the sound, regardless of its nature, the better. To others the kinder, gentler sounds of natural prey seem more appropriate. The reason for this lack of consensus is partly because bass attack acoustic lures for different reasons.
Bass, on the whole, are exceptionally curious creatures. As top dogs in the local food chain, they tend to throw caution to the wind. Anything new in their environment beckons them irresistibly for a closer look. Adding an unfamiliar sound only accentuates the novelty. Because bass don't have hands, they use their mouths to feel things out. They exhibit little hesitation in taking up foreign objects, feeling them out, and deciding from there what to do next. Many a bass has been on hook and line simply because it wanted to check out the new loudmouth kid on the block. Curiosity sometimes gets more than the cat.
Bass are nothing if not pugnacious. Indeed, their innate aggressiveness is legendary. As top predators tempered with little prudence, they commonly attack objects out of what in humans we would call a supreme lack of tolerance. A lure can quickly find itself in the mouth of a bass by simply being at the wrong place at the wrong time, much to the delight of the angler. By daring to announce their presence ever so boldly, acoustic lures just aggravate the bass all the more.
Finally, bass strike acoustic lures to feed. Predators are alert to the sounds their prey makes. They use these telltale cues of sound to identify, and home in on, unsuspecting morsels. Many prey species are known to make characteristic sounds while feeding. Others, especially during spawning season, let loose courtship calls and territorial warnings. Most, if not all, of these sounds lie within a bass' range of hearing and vibration detection. Hardbaits do not put out sounds anywhere close to those of natural prey. The subtle soft plastic baits, on the other hand, as they slide and slink along, generate vibrations that come much closer to natural sounds.
While natural sounds may work, the most attractive sounds will be those that best match a bass' sensory tuning, whether the sound is natural or artificial. The bass doesn't know the difference. It has no concept of natural, only whether an object matches what it perceives to be food.