SOUNDING OFF ON HARD LURES
Greg “Doc Lures” Vinall
By the time Doc finished high school he was a serious custom lure-making addict. So strong was his motivation to avoid a “real job” that he took to university, where he studied the only fishing-related course available — Aquatic Science. Fishing before and after, and even between classes, he started to build his new scientific knowledge into highly effective handcrafted custom lures. Decades on, Doc’s obsession with the science of fishing and the art of innovative lure making is stronger than ever. Each year he lures thousands of unsuspecting fishermen from around the world into custom lure making, knowing that many will never leave. He continues to masquerade as a Poindexter scientist, distilling the hard work of other scientists into a bunch of powerful fishing tips. With a mantra of “Grow old, but don’t grow up” Doc’s unique knowledge and quirky delivery puts him in demand as an author, speaker and presenter in the recreational fishing space. [click the image above to go to Doc’s website]
I’ll be blunt (it’s one of my many charms). If lure makers spent as much time making lures sound good as they spend making them look good, we’d have much more effective lures. So in this article we’ll explore how fish perceive underwater sounds — and how lure fishers can use sound more effectively.
Have you ever been in the vicinity of a packed children’s playground when somewhere, off in the distance, that faint, sweet melody of an ice cream truck comes into earshot?
Instantly that playground becomes a ghost town. Empty swings sway from the hasty departure of their last patron. Bicycles lay on the ground, their wheels still slowly spinning. The slides… Eerily silent.
Yep, if ever there was a timeless example of marketing genius, that infernal ice cream tune is it. Kids hear it from six blocks away — yet they can’t hear their mother screaming to put their shoes on from six steps away. Parents also hear that tune over the background noise and immediately brace for the inevitable chorus of “Can I have an ice cream?”.
Anyway, nice story. But I’ll bet you’re wondering what it has to do with fishing?
I often use the ice cream truck story in my lure fishing presentations because it’s the perfect example of how a simple, familiar sound can trigger a very strong reaction. A hard-wired, instinctive reaction. Once your brain links that tune with ice cream, it creates a permanent association that replays subconsciously every time you hear the tune. It can really take a lot of willpower not to reach for the wallet.
Certain sounds can invoke an instinctive, almost involuntary reaction from fish.
As a Poindexter scientist and lifelong custom lure mega-geek, I’ve spent a lot of time scouring the scientific literature for clues on fish behaviour and lure performance (I can’t understand why I don’t get invited to a lot of parties these days).
To put things in simple terms, fish are basically instinctive creatures that sense what’s happening in their environment and respond accordingly. Just as we learn to associate the ice cream tune with a sweet treat, fish can learn to associate a particular stimulus with a life experience. That’s why it’s often harder to get a strike in areas where there’s a lot of fishing pressure, even when the fish stocks are healthy. They’ve learned to be lure-shy.
Sound is just one of those stimuli, but it’s a far more important one than most people realise. For example, sound travels far further in water than it does in air. It also travels five times faster in water than air. Evolution has gifted fish with extremely sensitive hearing and they use sound for communication, mating, hunting and navigation. In fact, most fish rely on sound far more than they do vision — evolution wasn’t so generous with their eyesight as it was with their hearing.
Fish make strong associations between the sounds they hear and their life experiences, just like humans do. There are sounds that fish are hard-wired to detect over the background noise, just like humans. And those sounds can sometimes cause fish to throw caution to the wind — with some crazy, instinctive, spur of the moment results.
If you play your cards right, fish will usually hear your lure long before they ever see it, even in crystal clear, well-lit water. The decision to eat or reject the lure is made long before the fish ever gets a look at it.
If there was ever an opportunity to advance lure fishing, then optimising sound is it.
Underwater sounds are critically important for attracting fish to your lures, far more important than colour. Yet sound is the least utilised and least understood tool available to lure fishers.
Sure, 90% of the hard bodied lures on the market contain some kind of inbuilt, noise making rattle. It’s just that, generally speaking, very little thought or research goes into those rattles. In many cases they’re added almost as an afterthought, or to satisfy the expectations of anglers.
There’s a naive assumption among anglers that just because a lure contains a rattle then, a) fish will hear it and, b) fish will be attracted to the sound. It’s quite common for both of these assumptions to be proven wrong.
It’s a mistake to assume that because you can hear a rattle, so can the fish.
Actually, it doesn’t matter one iota what you can hear or what sounds attractive to human ears. All that matters is what fish hear and what attracts them, right? So let’s look beyond the marketing and test some assumptions about sound and lures.
From a fishing perspective, there are three key aspects to lure sound: Volume, frequency and quality.
Volume is self explanatory — and is usually the only thing that lure fishers fixate on. But in terms of sound, it should be the last thing we worry about. Yet, lure makers frequently go to plenty of effort to make their lure as loud as possible using metal rattles, glass or plastic chambers, lots of hollows in the lure body and so on.
Frequency is all about the pitch (or tone) of the sound. Low pitched sounds can travel further in water than high pitched sounds. Humans often assume that the underwater world is largely silent, because human ears don’t work so well below the water surface. Go figure! But using hydrophones, scientists usually find that there’s a chorus of low pitched sounds down there.
The truth is, low pitched sounds are more natural, more audible and travel further in underwater environments than higher pitched sounds. In fact, almost all natural underwater sounds are low pitched… which brings us to another important consideration: Fish can only hear a limited range of sound frequencies — much more limited than the range of frequencies humans hear.
I like to use the “silent” dog whistles as an example to illustrate this point. Dog whistles are only silent to human ears, dogs can hear them just fine. The reason for this is that human hearing tops out at a frequency of around 22 KHz (less if you’re a married man with well developed selective hearing), while a dog whistle operates at 24-25 KHz. So we can’t hear it. Blowing the whistle harder makes it louder, but we still can’t hear it, no matter how loud it is. On the other hand, dogs can hear up to 45 KHz so the whistle is easily within the dog’s range.
This is is precisely why I said that the volume of the sound your lure makes is usually not that important!
Okay, so now we have an understanding of the importance of sound volume and frequency, let’s talk about the quality of sound that is emitted from your lures.
The impact of sound quality on fish response is a little harder to put a finger on. It’s about the preferences of the fish, which can change by species and individual, depending on what experiences they have learned to associate with a sound. And it’s about the difference between sound and noise. To give another human example, a garbage truck could be a similar volume and frequency to an ice cream truck. But it’s a less pleasant sound and it’s unlikely to empty a playground from six blocks away.
In other words, just because fish hear a sound, it doesn’t necessarily follow that they’ll be attracted to it.
In fact, the wrong noise could send them scurrying the opposite direction. And making a unpleasant sound louder will send the fish faster and further. Think about how you’d personally respond to the sound of gunshots or police sirens. And the closer they are, the more alarmed you’d become.
If sound is going to be our friend, we need our lures to emit pleasant tones within the fish’s hearing range. All of which makes the idea of slapping a rattle into a lure with no real thought pretty silly.
Focus on the frequency and quality of sound, not the volume.
So we know that sound is important to fish and that it can turn them on (or off) before they’ve even seen a lure. We also know that fish don’t hear most of the sounds humans can. And we know that the huge majority of lure makers don’t give sound much thought. When a lure makes the perfect sound, it’s more by good luck than good management.
If we want to use sound effectively in our fishing as lure fishing enthusiasts, we need to know how to pick a lure based on the sound it makes.
So let’s dive a bit deeper into the sound frequency puzzle. And don’t worry, I’ll keep the science as simple as possible!
Over in the USA and in Europe there have been quite a few different studies on fish hearing. As a result, we know quite a bit about the frequency range that dozens of northern hemisphere fish species can detect. Here are the key points:
- Fish can be broken into hearing “specialists” and “non-specialists”. Specialists are more sensitive to sound and can detect a wider range of frequencies, often using their swim bladders to amplify frequencies.
- The hearing range varies tremendously between species, but overall the specialists can usually hear from around 0.005 to 1.5 KHz, with a few able to hear beyond 2 KHz (by comparison the human range is around 0.2 to 20 KHz).
- By far the majority of fish species can’t hear sounds higher than 1 KHz
There hasn’t been been a lot of work done on individual Aussie species yet, so we can only assume that our fish species will have similar attributes as the overseas ones. That said, one Australian team studying fish communication managed to record a chorus of 700 fish species, with none exceeding 1.2 KHz. I reckon that makes it a fair assumption that our fish species are not able to hear sounds much above 1.2 KHz, which matches the overseas data.
Human ears can hear sound frequencies to 20 KHz, most fish can’t hear sounds above 1 KHz. The majority of sounds we can hear, fish can’t — no matter how loud.
So, how can we know what frequency of sound our lures make and whether fish can actually hear it? The simplest way is to pick up a lure, give it a shake (hold the hooks so they can’t rattle) and see what it sounds like.
Lures that have one or more fairly large, knocker style rattles tend to make a lower pitched sound that’s often within the fish’s hearing range. Lures that have lots of tiny ball bearings floating around inside a hollow plastic body tend to make a high pitched rattle that fish often can’t hear.
As an aside, one of the key reasons I’ve persisted with making wooden lures for the past three decades is that in wood all rattles tend to be low pitched. And while they are quieter to our ears than rattles in hollow plastic, they’re much more audible to fish. They’re also more attractive to fish, in my experience.
Allow me to demonstrate! To prove my point I’ve taken the hooks off one of our favourite plastic hard-bodied Aussie lures, a size 1 (105 mm) StumpJumper and I’ve recorded the sound of the rattle. I’ve also made a 105 mm wooden replica StumpJumper with a single 6 mm chrome steel ball bearing knocker rattle. Below you’ll find two audio players — the one on the left is the sound of the original StumpJumper, the one on the right is my wooden imitation.
JJ's StumpJumper Size 1 (Plastic)
Replica StumpJumper Size 1 (Wood)
I’ve amplified these audio files for the purposes of making them easier to hear, but I’ve amplified both by the same amount, so you can still hear which rattle is the louder one.
So what did you notice about the two rattles? Did the plastic StumpJumper with it’s hollow body sound louder, clearer and higher pitched? Did the rattle in the wooden lure body seem softer and duller?
So which rattle would the fish hear better? Well, let’s take a scientific approach to answering that question.
I’ve analysed the sound frequencies of the two rattles and plotted them against the volume for each frequency. If it sounds complex, don’t worry, I’ll make it simple – and worth your while.
In the graphs to the left (click on them for a larger image) I’ve shown the frequency spectrum analysis for each of the rattles. The top one is the plastic StumpJumper and the bottom graph shows my wooden imitation of the plastic lure. These graphs show the that the rattle in the plastic lure makes sounds in a frequency range from around 50 to 7800 Hz. The wooden lure makes sounds from 50 to 7300 Hz, so a slightly smaller range.
As I’ve already discussed, fish tend to hear low frequency sounds, so in the inset charts I’ve expended that part of the spectrum analysis that the more sound-sensitive fish species can hear. Note that the single knocker rattle in the wooden lure emits a much stronger sound at lower frequencies. This means it is much easier for fish to hear the wooden lure than the plastic one, even though the plastic lure sounds louder to human ears.
Please understand that I’m not criticising StumpJumper. It just happened that I was commissioned to make some replica StumpJumpers for a collector and they were on my workbench when I wrote this post. A large proportion of commercial lures yield similar results to the plastic StumpJumper, which is just one of many reasons I prefer handmade wooden lures. And StumpJumpers are proven lures for our freshwater native species, so they obviously have plenty of other qualities that attract fish. But sound isn’t one of them. The rattle in a Stumpjumper is for fishermen, not fish.
Are you curious about what those rattles actually sound like to a creature with a hearing range from 50-1500 Hz? Cool! I’ve gone ahead and applied a filter that removes all sounds above 1500 Hz to each of the recordings .
Plastic StumpJumper (Filtered)
Wooden StumpJumper (Filtered)
Note that the amplification on these audio files is exactly the same as the previous ones. The reason the plastic lure is so much harder to hear after the high frequency filter is that volume comes from sounds that are outside of a fishes hearing range. And that’s for species that have reasonably good hearing (for fish). Other species can hear a lot less.
By contrast, the rattle in the wooden lure sounds similar after applying the high frequency filter to how it sounded before filtering. That’s because the sound it emits is stronger in the lower frequency ranges that are within the fish can hearing range. So the rattle in the wooden lure is much louder and easier for fish to hear.
For those with a curious mind, the difference is about more than just the size and type of rattle. Wood and plastic have different sound properties, with each timber has its own has its own resonance determined by the density and cellular structure of the wood. That’s why certain timbers are good for making musical instruments and why plastic guitars have never really taken off. Even when the density of the plastics match the density of natural wood the sound is different due to the physical structure of the raw materials.
If you want fish to hear your lures, train yourself not to be fooled by the volume of the rattle and instead focus on the pitch. Remember that larger rattles will always make a lower pitch sound than multiple small ones and that wood lures containing rattles are almost always audible to fish.
Pick a lure up and give it a shake, holding the hooks so they can’t rattle. Forget about volume, if you want fish to hear it you’re looking for a low pitched sound, that’s the key. Large, single rattles will always trump multiple small rattles and wooden lure bodies almost always trump plastic ones.
Before I wrap up this article, I’d like to circle back to the idea of creating a pleasant sound that attracts fish, rather than an unpleasant or scary sound.
So let’s imagine that by a stroke of luck you struck the jackpot and tied on a lure that fish can actually hear. Awesome start! Now you need to figure out whether the sound is working with you or working against you. In other words, is it a sound that fish like and are attracted to?
That’s a little harder to gauge because, like humans, fish can have personal preferences. Let me give another human analogy.
Imagine you drop by your favourite watering hole to pick up some take-away brewskies to bring home for a night in front of the telly. When you get to the pub they have a live band and the music is really good. They’re playing stuff you like and doing a good job of it. Odds are you might stop for a couple of cleansing ales, just to enjoy the band for a bit. Maybe you’ll even forget the telly and stay till late.
But what if the opposite was true? You decided to go out for a night on the town, but the local pub had an atrocious band playing your grandfathers favourite hits. Most likely you’ll grab some travelers and head for home. Or you’ll go to a different watering hole.
Fish usually hear a lure long before they see it, which is a double edged sword. If they like what they hear they can be switched on, lit up and ready to strike aggressively. If they don’t like what they hear they may be switched off before your lure comes anywhere near them.
A while back I designed some ultra-silent lures for US bass tournament pro’s. Often these guys would start out using rattlebaits and would do quite well on them. By the second and third day, the lake had been thrashed by thousands of anglers casting rattling lures and the fish had become wary of anything that made noise. A silent hard bodied lure was just the trick to knock out the competition on the final day.
That lure (pictured below) was so popular that I made it one of the projects for my lure making students. It’s become a hit here in Australia on cod and barra, which is pretty cool.
Anyway, the point of this example is that fish were initially attracted to the rattles but after some fishing pressure they quickly learned to avoid it. By switching to a lure that made no noise, the anglers were able to elicit reaction strikes and get back into the game.
By the way, a fish doesn’t have to have a personal experience with a rattling lure to make the connection. Schooling fish in particular pick up on the body language of their mates. If one or two fish react badly to the rattling sound of a lure the whole school can go off the chew.
And don’t believe that garbage about fish having poor memories, either! The story about a goldfish having forgotten what’s on the other side of the tank was spawned by pet owners wanting to make themselves feel less guilty about their bored pets. That association fish make between an unpleasant experience and the sound of your lure can be quite long lasting.
One final thought: not all fish species are attracted by noise and not all fishing scenarios lend themselves to the use of rattles. For example, a noisy rattle might well spook fish in a small mountain stream or quiet pond, especially if you’re targeting shy, skittish species. On the other hand, super inquisitive species might be attracted by a loud rattle. Or you might want more noise because you’re fishing in dirty water or low light where noise can make it easier for fish to find your lure.
The final message I’d like to impart: It can be very worthwhile to experiment with sounds, but until you understand that fish don’t hear lures the same way as we do, you’re shooting in the dark. Armed with the knowledge above, hopefully you’re inspired to give the sound of your lures a bit of extra focus. You might find yourself making different selections as you try and figure out which of your lures are ice cream trucks and which are garbage trucks!
And if you really want some control over the sounds your lures emit then maybe it’s time to think about having a crack at custom lure making. You’d be pleasantly surprised at how easily just about anyone can make highly effective custom wooden lures!