Have you ever pondered the big questions in golf? You know, those discussions or topics which inevitably bring curiosity to the forefront, especially when talking club design. Well, those are the topics which live in our heads too, so we thought, why not create something to explore them with each and every one of you?
Here at THP we have long held education as the ultimate pillar which has driven us for the last 17 years. Believe it or not, we have been at the forefront as innovators and leaders when it comes to releases, reviews, experiences, community testing, and any other number of things. However, it is education for which everything else has always stemmed from.
We pride ourselves on not just being part of these conversations but more importantly, driving them. You want to know the “why” behind things? We want to provide answers. After all, that is how you build a knowledge base to go out and discover what equipment works best for you, as opposed to letting some convoluted rankings list try to influence you via their own biases and motives. There is simply no better way to do that than to get into the weeds of it all and bring with us some of the best and brightest that the golf industry has to offer.
This marks the start of something new, deep, educational, and fun.
Although the topic possibilities are endless, we wanted to kick things off with one of the age old discussions, Sound and Feel, specifically in iron design. To do that, we brought in the big guns right out of the gate, none other than the incomparable Chris Voshall of Mizuno Golf.
The Sound and Feel Relationship
Is Sound also Feel?
This is a topic near and dear to my heart, and one that always brings some pretty passionate conversation when we are attempting to describe the feel of golf clubs. Naturally, there is the age old camp which places tactile feedback to the hands as the true decider of how something will “feel”, and there is some solid validity to that. Of course, barring any health issues or blasting your favorite tunes in headphones while out bashing golf balls, we don’t typically hit clubs in a situation with the absence of sound. As such, reality is that the sound of a club at contact will absolutely have a real impact on your perception of soft or firm, as well as pleasant or off-putting.
This was a big point which I was eager to ask Chris about in our conversations, as I honestly didn’t know where he would go with it. However, in the way only he can, the depth and breadth of the rundown is worth diving in on:
“Yeah, I agree with that comment, that sound is feel. You know what? What you are feeling from a golf club, or the sensation that comes from a golf club, a large percentage of that is audible. There’s obviously the tactile feel part, if you hit a rock, you’re absolutely going to feel something in your hand. But the perception of the quality, softness, and I’d say the character of the sound that’s generated is a huge part of what you interpret to be a specific feel as a golfer.”
In all honesty, the versus aspect of sound and feel by some out there is a point of contention which really shouldn’t be. Rather than trying to make them separate entities, they really are siblings when it comes to how we as golfers experience a golf club. Do either decide the key performance aspects like launch, spin, or forgiveness? Of course not. They do though impact our perception of those things, and that is why there are multiple aspects that are critical pieces of sound with feel.
Club design is all about nuance, and there is much nuance to what impacts the sound and feel of an iron.
Getting to the “Hertz” of the Matter
Before we dive into how the different design aspects of irons influence the bigger picture of feel, we need to take a quick detour into just what makes up the sound each of us experiences. You see, there are specific hertz frequencies which our ears receive that are critical in whether we decide a specific clubhead is pleasant, or harsh.
The way Chris puts it:
“Essentially a sound wave, the character of a wave and the frequency of that wave is measured in Hertz. The hertz is the is the unit for the length of the wave. So, what we’re looking at when we digitize and measure sounds, is what peaks are occurring, at what frequencies.”
For Mizuno, the focus goes deep into the peaks of the sound an iron is producing. They target the “modes of vibration”, those very sound peaks. By looking at six different modes, a bigger picture is painted. The first couple have much to do with the golf ball and turf interaction, while the others come predominantly from the club head. The key though is on the hertz range which we humans can truly pick up, and then how each of the modes coexist without cancelling one another out.
That seems like a lot to digest, but Chris broke it down amazingly well when we talked by saying, “We’re really just looking within that range (3,000-12,000Hz) and then trying to dial in those frequencies to be not only the most pleasing frequencies on their own, but also, we talk about what we call harmonic impact technology, the harmony that exists between those different modes.”
What determines those hertz ranges though? You can parse it down to three critical elements for any iron design being made, materials, geometry, and processes applied therein.
Living in a Material World
If I were to ask you how much you think the material/metal that an iron is made out of impacts the overall dance between sound and feel, you would likely put it way up there. Yet, in the real-world hierarchy of importance, it might not be as high as expected.
You have likely read hundreds of iron release articles which dive deep into the material, or materials, that are being used in the construction as a key design element. While that absolutely does matter in terms of strength and durability, the reality is that most of those materials on their own are far closer to one another than we grasp. You see, it is how it is being used that differentiates them all.
As he does so well, Chris has a clean way of breaking it down a bit more:
Material choices are made because you have thickness requirements.
Let’s just say, for example, a maraging steel face. You pick that because you want to go thin. When you go thin like that, the harsher feel doesn’t come from the maraging steel as a material, it comes because it got thinner.
As consumers, it often feels like we live within a constant arms race with irons. That push to utilize materials which can be taken thinner is real because it does mean more speed, but that thinning can have a definite impact on the sound or feel. That said, it still doesn’t impact things to the degree most of us think, but how it is shaped in terms of geometry absolutely will.
If you want to imagine things in terms of hierarchy, Chris had a very concise way to think about it:
The material itself I’d say is a third tier effect. However, what that material indicates about the overall engineering has a major effect.
It’s All About the Angles
Oh yes, Geometry is more than just a class you either loved or loathed back in your much younger days when the future was bright, and hairlines were intact. In fact, it is arguably the most critical part of the sound and feel relationship if you want to try and rank things.
When you hear the term geometry as it pertains to irons, you likely think “shape”, which is absolutely correct. That “shape” aspect though, is much more impactful than just looks, it takes those previously mentioned material and acoustic pieces of the puzzle and put it together, good or bad. Chris has a particularly unique take on it:
“I’ll say that the the sound character, the frequencies that the club is vibrating at, are very geometry dependent. The geometry of the head is going to dictate everything. How thin is the face? How large is the face? How large is the club from toe to heel. How thin is the sole? How thick is the top line? All those things are going to dial in what the frequencies are. But again, frequency and that that sound is just one aspect of how much you feel.”
As you can see, there are MANY specific focal points that we could get into weeds about where it concerns the impact of geometry in sound and feel within irons. This time around though, heavy emphasis goes into two specific areas that I was able to discuss with Chris, an irons cavity as it pertains to face thickness, and the topline.
The geometry of the cavity and face thickness in modern irons are very much intertwined. In that chase for speed, we have seen the application of technologies like Cup Face which stretches the face into the sole as well as Mizuno themselves working to extend the thinner face of their Hot Metal irons even into the heel and toe to maximize performance. By going thinner and elongating that thin area, you add speed as well as shifting the saved mass to the perimeter of the head which can massively increase playability across the face.
The thing is, moving all that mass and thinning the face does have a cause and effect situation if nothing else is done. When you create any cavity, there is now a thinner area that will vibrate more and at a lower frequency that moves the sound to a harsh and less pleasant place. This is why in multi material CB iron (meaning not one-piece forged CB’s) you see ribs and badging which bring reinforcement that puts the frequencies back into a realm that blends the power of the thinner face with a feeling that is more whole and less off putting.
With all this in mind, I asked Chris to compare the effects of geometry from a modern iron to that of a one-piece design like a muscle-back, which for many remains the ultimate in “feel”, when you don’t miss that is.
“In a one piece design, the MOI is not going to be as high because the mass doesn’t move around as much. But the sound is traditionally better because a thicker face is more reinforced. So, it all comes to the reinforcement of a face when you put a cavity on it, and then you don’t reinforce it anywhere, you are at the mercy of that face thickness.”
Why is the Topline So Important?
Though the deflection of the face impacts the sound and feel at impact, and the reinforcement is a key element in tuning that, the topline plays a role which might surprise you. So often we nitpick the topline in these modern irons, I know I am extremely guilty of that, and because of that companies have continued to find ways to trick our eyes without moving to a true thin topline as we see in the one-piece irons. Chris explains it like this:
“Top line is such an interesting thing because the player who wants the thinnest top line available does not want the feel of the thinnest top line available. Those two things work against each other. I talk about geometry as how a club is reinforced and how do you get the sound frequency up. The topline is one of the thinnest parts of the golf club, which means that it’s an area where the frequency is the lowest. At the top line, if you get it really thin, the amplitude is large. When the amplitude is large, that means volume goes up and the frequency goes down. So, all that to say, a player who wants a thin top line wants the feel of a thick top line.”
What About Hollow Body Irons?
Of course, to work around such things, we have seen innovation pushed into the era of hollow body irons. This helps tame many issues of reinforcement which companies battle with the thinner faces, and that means bringing the sound and feel to a more enjoyable place. In fact, the hollow body has taken advantage of design geometry to the point that they are becoming better feeling than the open cavity designs.
The conversation of hollow body is interesting because it looks like a thick geometry, but it’s not. The face is thin, but then we’ve covered it up. By doing that, you get kind of the freedom to move that mass around, because it’s not just all concentrated right behind the face. You still have a thin face, but the sound character changes because you’re reinforcing the back. So essentially the hollow body design is a way of making a cavity back thin face golf club more reinforced like it’s a thicker face.
Is your head spinning yet? Hopefully not, but if we want to have a better understanding of how sound and feel are created and managed within modern irons, these aspects are critical. There are clearly some baseline rules which are in play for companies when it comes to creating sound and feel, but those rules are nothing without the right processes. In fact, in the case of Mizuno, it is a key component to why they are as revered as they are when it comes to iron.
It Really is a Process
Historically, better players always discuss “feedback”, specifically being able to “feel” where the strike occurred and not having it blur into the background. For many years, you would look towards smaller one-piece irons to make sure you got feedback and the sound as well as feel you desired. This is where things turn more nuanced depending on which companies you talk to. Fortunately for us here, there is arguably no brand more in-tune to discuss it with than Mizuno.
All of the aforementioned pieces of an irons design are critical to the sound and feel dance, they also all come together to be very important in the duration of that feedback. In both the audible and tactile reality of irons, the length of which vibrations happen from all interactions (turf and ball) is what ties it all together. These lengths are what give the feeling of power/hot irons which the ball feels like it jumps off the face, or those who give such an elongated sensation that it feels like the ball almost melts into the club head. To get there, companies all have their own specific processes that they use. When it comes to Mizuno, you know at the forefront will be cast versus forged.
At its most basic, the age old forged versus cast conversation is all about grains. A cast iron is poured into a mold which means it is absent those grains and can inevitably have impurities which create air pockets within their structure. Forged irons though, because of the process of being pressed into shapes, have internal grains which will carry the vibrations and frequencies. The longer the grains, the longer, and better, the sound and feel you will receive at impact.
To describe this, Chris uses the experiment of two glasses of water, one still, and the other sparkling. If you tap the glass with a utensil, then the still glass will ring while the other is met with a short, dense, thud. He states that to be the exact same thing with golf clubs, which leads further into his explanation that:
“You could take two geometries that are the exact same, that are creating the same decibel levels, the same frequencies, the same sound character. But if one is a longer sound than another, you’re going to perceive something different. That is where we talk about at Mizuno, our grain flow forging technology. When we stretch and bend the club and have very long grains, the longer the grain, the longer that that vibration is going to happen. So even if somebody straight up copied our design, the geometry is identical. It’s not going to vibrate as long if the process is different.”
Keep in mind though, that within bigger processes like forging, there are also smaller ones that differentiate. For Mizuno, their Grain Flow Forging is a step above, and it creates significantly longer grains than other forging processes, that means more sound and feel. However, even that can go deeper as you get into fully forged irons like Mizuno creates, versus other popular designs which forge parts of the whole, which shorten those grains that carry the feedback considerably, leading to sharper sound and feel. This is where other brands often have to bring in another process to bring things back around.
Vibration dampeners, foams, and stuff like that inside a golf club, they basically kill duration of how long that club will vibrate.
In recent years, to make those partly forged designs and ultra-thin faces work, many manufacturers have put considerable innovation into various dampening materials and internal fillers. These materials of course can alter the frequency ranges into something much less harsh and instead into a realm which our ears and hands associate with “soft”. It might not surprise you that both Chris and Mizuno have a very specific take on this.
“That’s where Mizuno will get on a little bit of a soapbox here,” Chris explained, “So, vibration dampeners, foams, and stuff like that inside a golf club, they basically kill duration of how long that club will vibrate. They don’t necessarily change the frequency because the head geometry is going to dictate that, but they’ll change how long you feel that golf club.”
While you might say, “so what?” to the above, it actually brings a deeper thought process. Perhaps as we are being told about how all of these materials out there in irons help make for a “soft feel”, they are just creating less of the harsher and/or sharp feedback that would happen in the absence of the materials. That in itself isn’t necessarily bad, but it also means shortening the time of feedback, which lessens strike location awareness, and creates a tangled web of feel and sound possibilities.
The Long Way Around
If you have kept reading this long, then you no doubt have a lot to digest. Though some of you might have hoped we would present to you some sort of dramatic revelation that defines sound versus feel, that was never the goal here as the reality is they both go hand in hand when it comes to iron design. What should be enlightening though is getting the input of Mizuno’s Chris Voshall on the battle for sound and feel, as well as how better engineering matters.
These pieces are our way of bringing the deepest dive possible to you all. Not only will it hopefully expand knowledge, but perhaps it will also make it so the next time you are discussing irons and get asked, is it sound or feel, it will be your turn to educate.
