Unless you get a chance to try out every motorcycle helmet available on the market, figuring out which ones are the “quietest” can be quite the challenge. Add to that the fact that no two riders are alike, and have different perceptions of what is loud, and things just got more complicated. The problem is that we don't get to test the helmets we're interested in on the road. Most retailers won’t let us take a demo out for a test ride to figure out if it works for us or not, and manufacturers don't usually publish or even test their products' decibel measurements.
So, we have to compensate for the lack of information by reading professional reviews and users’ opinions on forums, and hope for the best. We decided to do some digging to figure out what makes a helmet noisy and came up with a few suggestions of features you can look for to help keep the decibels to a minimum.
Why Do You Want a Quiet Helmet?
Riding is a pretty noisy affair. Between the wind, the engine, the road, and the traffic, things can get loud enough to damage your ears. It might not sound like it, especially if you’re used to cathartic chaos, but a motorcycle engine alone can reach a sound level of up to 95 decibels (dB). According to the Centers for Disease Control and Prevention (CDC), that’s enough to cause permanent hearing damage if the exposure lasts longer than 50 minutes. That means that your weekend joyride can cause more damage than you imagined—damage that is irreversible.
Despite that very real problem, few manufacturers advertise their products’ ability to protect a rider from prolonged exposure to road noise, let alone their decibel readings. We don’t know for sure how quiet or not helmets are unless we test them for ourselves.
Companies such as Schuberth test their lids in wind tunnels and gladly share the results, but they’re the exception to the rule. Schuberth even took things a step further when it inaugurated its upgraded aeroacoustics wind tunnel and climate testing facility in 2015. As far as we know, it’s the only manufacturer to include a decibel rating in its sales pitch.
In 2018, the results of an in-house study by Dutch motorcycle magazine Promotor suggested that most motorcycle helmets are pretty useless against the road noise. The magazine tested a selection of ten mainstream helmets at 50 km/h (31 mph), 100 km/h (62 mph), and 150 km/h (93 mph) to find out just how noisy mainstream products they can get.
It turns out that the best-performing (unidentified) helmet the team tested got a reading of 85 dB at 31 mph. At 62 mph, the sound level reached 100 dB. The average sound reading for the entire sample was of 88 dB at 31 mph.
What Makes a Helmet Noisy?
Ok, so helmets aren’t exactly good at the whole soundproofing thing, but why? What makes motorcycle helmets so noisy? We turned to a British study to try and find the answer.
In 2011, researchers at the University of Bath in England published a study about "aeroacoustic sources of motorcycle helmet noise” or, simply put, where helmet noise comes from. The researchers considered the following factors: the helmet’s wake and boundary layer—or, how air flows on the helmet’s surface and the resulting turbulence it creates—as well as the chin clearance and opening at the neck.
“The helmet wake, while being shown to contain turbulence over a wide frequency range, did not prove to be a signiﬁcant source of at-ear noise,” sates the University of Bath study. “An investigation of the helmet boundary layer was conducted at several locations around the helmet surface. These regions did not measurably contribute to the at-ear noise.”
It turns out that the helmet’s design and the presence of aerodynamic components such as grooves and wings might reduce drag and resistance, but they have very little impact on how noisy the helmet is.
Based on the data, the fitting at the neck seems to be the main source of helmet noise.
“The third potential noise source investigated was the cavity under the helmet at the chin bar. Investigations in this area were conducted using a microphone placed at the center of the mannequin chin. After conditionally removing the contribution of tunnel noise a high coherence was achieved between this region and the at-ear sound between 0 and 1000 Hz. Helmet angle and ﬂow speed were identiﬁed as key factors governing the production of sound from this region.”
While quite revealing, the study didn’t consider several factors. For instance, the researchers acknowledge that their study did not take the rider’s body and the motorcycle structure (fairing) into consideration. Keep in mind that the size of the windscreen and the type of fairing affect how much wind reaches your helmet and influence how much noise you perceive. They also recognize that the sound levels vary with how the helmet fits the rider’s head—the opening under the chin will incidentally vary in size and shape.
The research also didn’t take helmet features such as visors, seals, vents, and modular chin pieces into consideration. Any opening or ill-fitting component can cause additional noise. If you’ve ever had to deal with a whistling visor, you can vouch for this. That being said, by knowing that causes the noise, it becomes easier to counteract it.
What Features Should You Look For?
We have a long way to go before we see helmets that efficiently protect our hearing hit the market, and chances are that when the technology reaches that coveted level, we’ll have to pay the price of innovation.
In the meantime, what can we do to protect our ears? As Promotor’s study proved, there is no perfectly sound-proofed helmet so what are the options? The good news is that there are a few things we can look for in a helmet that will help block out the noise. Keep in mind that none of those features alone will save your ears; a combination of several will provide you with the optimal protection.
Based on the University of Bath’s results, a thick, well-fitted neck roll and the presence of a chin guard and/or a windjammer should help block out some of the noise by reducing the flow of air that enters the lid. You will, of course, want to try the helmet on to determine how well it fits on your head and around your chin and neck. The better the lining and padding around the head and neck fit your head, the better impact and noise protection the helmet will provide.
Look at helmets with a good-quality shield as well. Test the shield and its mechanism to see that it seals properly when closed. Is the visor’s material thick and sturdy or flimsy and easy to distort? Does the mechanism press the visor against the rubber seal or does the closure feel light and ill-fitted? A tight-fitting visor will help reduce the risks of dealing with avoidable noises like whistling.
The same applies to the air ducts and vents: if the materials and closure systems are flimsy and low quality, chances are they might get caught in the wind and increase the noise level. Consider that a single-piece, full-face helmet is also quieter than a modular or a 3/4 model designed with additional opening and seals.
If your budget allows it, premium helmets such as Schuberth and Shoei are widely recognized as some of the quietest products on the market. Schuberth claims that its C4 full-face model limits the noise to 85 dB. You can also shop for smart helmets like those in Sena’s Momentum lineup that feature integrated headphones and use active noise cancellation to help cut down on the exterior decibels.
Ultimately, the most popular, efficient, and inexpensive ear protector you can buy is a pair of earplugs. Sadly, while they’re generally socially accepted, they are considered illegal in a few States. According to AAA, the use of earbuds while operating a vehicle is forbidden in Alaska, California, and Maryland. Ohio appeared on the list as well until recently, when the use of earplugs by motorcyclists was legalized earlier in January 2020.
Good helmet designs will help more than they will harm but you might want to double down on your ear protection and make sure your new lid checks as many boxes as possible. Good materials and a good fit can go a long way.