A bass boat settles down to a quiet drift over a shallow point extending into a vast basin of open water. The angler picks up a rod, unhooks a BB-filled minnow plug from the rod’s first guide and launches a long, downwind cast. Then he begins his familiar, steady retrieve, without a clue that-for better or worse-his rattling lure is broadcasting a din to every bass within a quarter-mile of the boat.
The characteristics of underwater sound are truly a believe-it-or-not story. Before man was a technological presence in the oceans of the world, it’s believed that pods of gray whales, using their highly developed language of “songs,” could audibly communicate with other schools at distances of up to 6,000 miles. What’s more, these songs are not highly specialized sonar signals, but sound signals that fall well within the frequency range of the human voice. Today, however, due to the racket of large-scale shipping and other sources of submarine noise pollution, that hearing range has been cut to a couple hundred miles at best. It’s no wonder that these communication-dependent mammals frequently lose their bearings and become beached.
Extreme examples of animals using sound in an air environment-such as owls acoustically locating prey in darkness and bats using sonar to catch insects in flight-pale in comparison to what fish and aquatic mammals can hear. In studies, blindfolded porpoises have distinguished between two cylindrical rods that differ in size by only a hundredth of an inch by emitting clicking sounds and analyzing their echo.
So, how do whales, porpoises…and bass achieve such feats of aural excellence? Count out advanced ear development. In bass, that organ is simplicity defined. The fact is, the dynamics of underwater sound transmission are so impressive that most fish and aquatic mammals simply don’t require the sophisticated ears that have evolved to capture airborne noises.
The Water Medium
For humans to hear it, sound must be collected with the outer ear and funneled through a small hole to resonate the eardrum, which then conveys the sound through a series of tiny bones to the inner ear. Animals that possess large external ears and ear openings, like foxes and deer, can hear much better than animals with relatively small ears, like people.
But that’s in the terrestrial world. The body of a bass is about the same density as water. Sounds from every direction pass right through the fish, virtually unhindered, to its inner ear. Therefore, there’s no need to collect sound with elaborate external appendages. Furthermore, sound travels at 1,087 feet per second through air; it travels at 4,818 feet per second through water. So efficient is the transmission of sound under water that the energy of an exploding firecracker can seriously injure or even kill a submerged man. (On an interesting side note, the ability of sound to travel from one medium to another is dictated by the difference in density between the two media. Water is 800 times denser than air, and allows only one ten-thousandth of the sound energy from above water to penetrate the surface. Which is why your partner’s barking at you to “shut up, you’re spooking the fish” is probably misplaced criticism.)
**Dinner Bell or Death Knell? **
So what do bass hear when a fisherman retrieves a noisemaking lure like a Rat-L-Trap through the water? It is certainly not a natural sound. If minnows made that kind of a ruckus there would be so much background noise under water no fish could make sense of the acoustic riot. Still, I believe there are times when such sound chambers in a lure are helpful, just as there are times when they are not.
My belief that even unnatural sounds can sometimes be helpful is based on several factors. Chief among them is the fact that a bass is a predator, and one of the fundamental predatory principles is optimi. Anything a predator senses in its environment is viewed first and foremost with the “hope” that it represents a feeding opportunity. However natural or unnatural a stimulus may seem, it is a bass’s instinct to investigate and determine whether it amounts to a chance for a meal.
Most of the ways humans locate sounds are based on the fact that sound travels so inefficiently in air. Amplitude drops off sharply with distance, so we use clues like loudness and differences in volume between the left and right ear to locate the source of a sound. Conversely, sound travels with such incredible efficiency under water that a rattling lure produces almost the same volume at 200 yards as it does when it’s only a few feet away. So the volume of a noise is of almost no help to a bass in locating its source. And because waterborne sound passes virtually resistance-free through a fish’s body, the noise reaches both of the fish’s ears at the same time without giving any impression of the sound’s direction.
Water’s efficiency as a conveyor of sound is a product of it being non- compressible (unlike air, it can’t be squeezed; if it could, the weight of the liquid above it would collapse water at the bottom of the ocean into a solid mass), which is why sound moves through water much as it would through a solid substance. Imagine workmen servicing a radiator pipe in an old building. Once the hammering starts, you might have to look around to assure yourself the banging is not being done in the room in which you are standing, even though the workers might be several floors and a considerable distance away. But, if that particular pipe is not connected to your radiator and you can even faintly hear the workmen through the walls, you’ll have a fairly good idea of which direction the noise is coming from. Put another way, if you’ve ever heard the sound of a boat engine from under water, you know that to place the source of the sound you needed to lift your head above water to hear the sound in air.
Now, imagine the quiet under- water world of the bass being invaded by the loud sound of a rattling lure. The fish’s senses are aroused, and curiosity brings it out to look for the source. Unaware that the lure is creating the sound, the bass spots the plug, ignores the buzzing and strikes. In this instance it could be said that an unnatural sound had a positive influence on the catching of the fish. Still, the influence was incidental.
Sweet Sounds
Sound, like any other aspect of a fishing lure, is a tool for anglers to use when the time is right. Neither I, nor anyone else, can tell you all the rules for determining the best time to use sound, but I can tell you that it is certainly not “all of the time,” as purveyors of rattling lures would love to have you believe.
It is also important to define the type of noise a lure makes. Subtle, relatively quiet clickers, like those inserted into plastic worms, are less likely to be off-putting to fish than a hollow plastic plug filled with BBs or a slab of lead. I reserve the use of the loudest lures for deep water and open spaces, or for situations when the fish are extremely active and responding to things like bright colors and fast retrieves.
When I’m after savvy, more experienced fish, I try to keep my approach as true-to-life as possible, even though I’m aware that there are plenty of big fish caught on noisemaking plugs. Some of the most natural, albeit quiet, noises emitted by lures are those made when they bump rocks, trees and other underwater structure. Perhaps this is one reason for the long-standing success of lures that have always been categorized as “quiet,” like soft plastics. Their action comes from erratic retrieves and from contact with underwater objects-contact that creates subtle sounds bass are accustomed to hearing from their natural prey.
Other natural sounds you can use are the surface disturbances made by poppers, prop baits, chuggers and even buzzbaits. And if you’re wondering where spinnerbaits-one of the oldest and most consistent producers of bass-fit into all of this, consider this little-known fact: Tests have proven that spinnerbaits are virtually soundless in the water, their blades turning in one direction in harmony with the flow of the water. The throb we feel during the retrieve, the one most of us think is caused by a violent under-water vibration, is simply the weight of the blade tugging on the line, like an out-of-balance tire shaking the steering wheel of a car.
Spinnerbaits are consistent with the rules of “quiet baits,” in that they are much more effective when they’re fished through, or bounced off of, underwater structure, creating their version of a natural sound. In that sense, bass fishing is a lot like deer hunting: The soft sound of a twig breaking behind you in the woods can be much more important than the loud roar of a jetliner overhead. can use are the surface disturbances made by poppers, prop baits, chuggers and even buzzbaits. And if you’re wondering where spinnerbaits-one of the oldest and most consistent producers of bass-fit into all of this, consider this little-known fact: Tests have proven that spinnerbaits are virtually soundless in the water, their blades turning in one direction in harmony with the flow of the water. The throb we feel during the retrieve, the one most of us think is caused by a violent under-water vibration, is simply the weight of the blade tugging on the line, like an out-of-balance tire shaking the steering wheel of a car.
Spinnerbaits are consistent with the rules of “quiet baits,” in that they are much more effective when they’re fished through, or bounced off of, underwater structure, creating their version of a natural sound. In that sense, bass fishing is a lot like deer hunting: The soft sound of a twig breaking behind you in the woods can be much more important than the loud roar of a jetliner overhead.