Extreme examples of animals using sound in an air environment, like owls acoustically locating their prey in total darkness or even bats use of sonar to catch insects in flight, pale by comparison to what fish can hear. The simplicity of the ear of the bass belies its incredible ability to discern underwater sounds. The fact is that the characteristic dynamics of sound in water are so impressive that they simply do not demand the extremely sophisticated ears that have evolved for hearing airborne noises.
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 only 1/10,000 th of the energy makes it through the surface into the water. Talking in the boat is unlikely to spook fish.
Our bodies, like those of the fishes, are about the same density as water, so, for us to hear it, sound must be collected with the ear, funneled through a small hole to resonate the eardrum which conveys the sound through a series of tiny bones to the inner ear. This is why animals with large ears and huge openings, like the fox or the deer, can hear so much better than people. When a bass is immersed in water of the same density as his body, sound from any direction can pass virtually unhindered right through him to his inner ear. Sound in the air travels at 1087 feet per second and, at 4818 feet per second underwater.
So what do bass hear when a fisherman retrieves the Original Fishing Snake™ with Hawg rattle through the water? It is certainly not a natural sound, because, if minnows sounded like that, there would be so much background noise underwater that no fish could make sense of it. Even so, it might surprise you to know that I believe there are times when such sound chambers in a lure are helpful as well as times when they are not. There are several factors involved in this conclusion that even an unnatural sound can sometimes be a positive. First among them is the fact that a bass is a predator and one of the fundamental predatory principles is optimism. Anything the predator senses in his environment is viewed first and foremost with the "hope" that it will provide a feeding opportunity. However natural, or unnatural a stimulus may seem, it is up to the bass to investigate and determine whether it amounts to a chance for a meal. Most of principles we use to position sound in the air are based on the fact that sound travels so inefficiently in air. Since amplitude drops off sharply with distance and most of the sound energy bounces off of our bodies and surrounding objects, we can use clues like loudness and difference in volume from one ear to the other to help us locate the source of a sound with remarkable accuracy.
Sound travels with such incredible efficiency underwater that a rattling lure sounds as loud at 200 yards as it does only a few feet away. Since sound passes through the body of a fish with no resistance, equal amounts reach both ears at the same time. There are no position clues since water is non-compressible, and sound moves through it much as if it were a solid substance. Imagine workmen servicing the radiator pipes in an old building. Once the hammering starts, you might have to look around to make sure it is not in the same room with you, even though the source might be several floors and some considerable distance away. But, if that particular pipe were not connected to your radiator and you could even faintly hear the workmen through the walls, you would have a fairly good idea of which direction the noise was coming from. This clearly illustrates the difference between locating sources of sound in air or water.
Now, imagine the quiet underwater world of the bass being invaded by the loud buzzing sound of a rattling lure. His senses are aroused, and curiosity brings him out to look for the source. He sees the lure, and, with little awareness of the source of the sound, ignores it and strikes. In this instance it could be said that an unnatural sound had a positive influence on your catching of the fish, even though the effect was incidental.
Despite what we read in fishing journals, the lateral line is really not involved in this process. Early in this century, American scientists proved the purpose of the lateral line by cutting its connection to the brain entirely and testing these fish against normal fish. The only finding was that the normal fish were able to respond to extremely low frequency vibrations, while the altered fish were not. Later studies in England confirmed this, finding that the vibrations detected by the lateral line were so low in frequency that they would likely not be detectable by the ears at all.
Sound, like any other aspect of a fishing lure, is a tool that is available 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 it is not "all of the time", as purveyors of rattling lures would have you believe.
It is also important to define the type of noise the lure makes. Subtle, relatively quiet clickers, like those inserted into plastic worms would be less likely to have an adverse effect than a hollow plastic plug filled with BB's or a slab of lead. I reserve the use of the loudest lures for deep water and vast open spaces and for situations where the fish seem to be extremely active and responding to things like bright colors and faster retrieves.
When I am after the wily, more experienced lunkers, I try to keep my approach as true-to-life as possible, even though I am aware that there are plenty of fish caught on noisemakers. Some of the most natural noises emitted by lures, even though they are not loud, are those made by physical contact with underwater structure and other objects. By now you should know that fish still hear them at great distances underwater. This is perhaps one reason for the long-standing success of lures that have always been considered "quiet", like soft plastics. Their action tends to come from erratic retrieves and contact with underwater objects. This creates sounds that bass are accustomed to hear coming from their natural prey.
Other natural sounds you can use are the surface disturbances made by poppers, prop baits, chuggers, and even buzzbaits. If you are wondering where spinnerbaits, one of the oldest and most consistent producers of bass fits in, consider this little known fact. Tests have shown that spinnerbaits are virtually soundless in the water. This is because the blade turns in one direction and in harmony with the flow of the water. The throb we feel and most of us think of as creating an extreme underwater vibration is simply the weight of the blade tugging on your line, like an out of balance tire shaking the steering wheel of a car. Spinnerbaits are consistent with the rules as well, in that they are much more effective when fished through and bouncing off of underwater structure, creating their version of a natural sound.
When it comes to sound fishing advice remember that the soft sound of a leaf rustle or a twig breaking behind you in the woods can be more disturbing than the loud roar of a jetliner overhead. Here's hoping that a better understanding of what a bass hears will connect you with the fish of a lifetime. |
