HYPERACUSIS CENTRAL

The strongest hearing protection available: Creare’s Flight Deck Cranial

by | Jul 4, 2024 | Living with Hyperacusis | 1 comment

The following is a product review from one of our staff writers.

Late last September, I obtained the strongest hearing protection available: the Creare Flight Deck Cranial (FDC). This helmet is designed to overcome the limits of traditional hearing protection in extremely high noise environments, namely, the flight deck of US Navy aircraft carriers (Dietz et al., 2011). The authors show that by attenuating bone-conducted sound that passes through the skull, the helmet provides more protection than earplugs worn with earmuffs (also known as double protection). Wilbur et al. (2023) report that with foam earplugs worn under the FDC, the Noise Reduction Rating (NRR) is 38 decibels. The FDC has also been tested in blocking impulsive noise, such as gunfire (Clavier et al., 2012). In this article, I break down my experience with the helmet in terms of attenuation, comfort, looks, and ideal use cases for hyperacusis sufferers.

For my testing of the helmet, I wore either Moldex Soothers, SparkPlugs or Pura-Fit (NRR 33 foam earplugs) underneath. For the purposes of this review, when I refer to the helmet, I mean the helmet worn with earplugs, while double protection means I wore earplugs and Peltor X5A earmuffs. When I first tested the FDC, I noticed that typing on my computer was totally inaudible. I felt the keys hitting my fingers, but the keystrokes themselves were silent. Even with my mechanical keyboard switch tester, I could only hear the loudest switches on it.

At one point, I took the trash cans out to the street. Our driveway has a lip that drops down about an inch. This lip causes the trash cans to slam, producing a loud “thunk.” With the helmet on, this slamming sound was tolerable. However, after my latest setback, I have to be much slower and more deliberate when taking the cans out to the street. Another situation at home involved a new dishwasher that was much quieter when running, however shutting it would produce a loud snap. While wearing the helmet and closing this dishwasher multiple times, it was tolerable, albeit with some discomfort. In double protection, however, just one snap of the dishwasher immediately proved painful and injurious to me. The helmet works much better than traditional hearing protection for sudden loud sounds.

As Figure 3 in Dietz et al. (2011) shows, the helmet performs very well across all tested frequencies, but it excels in attenuating high-frequency noise. At my prior level of noxacusis, I experienced this firsthand with a drawer in the kitchen containing many metal measuring cups, can openers, and other utensils. Purposefully digging through the drawer in a way that made things clank was comfortable in the helmet. On the other hand, in double protection, the noises made in the drawer caused me pain and I had to be careful when going through it.

One day, my dad was running the hedge trimmer in the backyard. The helmet managed to completely cancel the noise as I stood at our kitchen window while he revved the trimmer to the max. For my final assessment of the FDC’s ability to attenuate noise, I wore it as a passenger in my mom’s Audi A6 on the way to a doctor appointment 35 minutes away. Riding in the car with it on cuts road noise more than double protection, however the most noticeable difference is that other traffic seems to be essentially inaudible. While it would be useful to evaluate the performance against an emergency vehicle siren, I’m fortunate that I haven’t been near any with the helmet on so far.

As for comfort, the helmet is relatively hard on my jaw. I find that Peltor X5A muffs with HY80 gel cushions are much more comfortable. Also, given the nature of a helmet, the FDC puts a significant amount of pressure on the top of my head. The helmet is heavy, so you feel the weight of it on your neck. However, I don’t use the chin strap. So far, the longest I’ve worn the helmet continuously is about 2.5 hours. When wearing the helmet in the car, I must recline back further than I would normally, since resting against the headrest pushes my head forward and I’m tall enough that the helmet will touch the roof of the vehicle.

As for looks, it’s very bulky and stands out, but that isn’t an issue to me with the severity of my noxacusis. It feels very durable and well-made, featuring a removable chin strap. I took off the strap right away. For reference, I have a large head. I used a tailor’s tape to measure my head circumference (about 23.5-23.75” or 59.69-60.33cm). This corresponded with Large+, the largest helmet size available. When it comes to putting it on, there’s a bit of a trick to it. One must spread open the ear cups sufficiently wide to clear the user’s ears. If I don’t do it correctly, it crushes my ears until I remove it and try again. Taking it off, one must again spread the ear cups so that it will come off while pushing upward. It takes a bit of practice to get the motion down, but otherwise, it’s very user-friendly to put on and take off.

In concluding this review, I would like to briefly discuss use cases for hyperacusis sufferers. Due to the comfort issues, I believe that this hearing protection device is most useful for brief or sporadic usage, rather than heavy use throughout the day. My jaw, top of my head, and neck find it uncomfortable to wear, while on the other hand, the attenuation it provides is unmatched. I would say situations in which one is exposed to power tools, sudden loud sounds (snaps, bangs, and clanks), and especially high frequency noise is where the helmet really shines. It may also be useful for long travels. Since the helmet is a passive device, it does not suffer from the issues that some hyperacusis sufferers (like me) have with active noise-canceling (ANC) headphones. As there are no electronics within the helmet, this means there are no beeps, low battery alerts, ringtones, or other sounds generated by the device in the user’s ears (all of which can occur with ANC headphones). All in all, the FDC serves as an excellent addition to the hyperacusis sufferer’s hearing protection arsenal. I’d like to thank Kirk Ohnstad at Composite Materials Research and Development for providing me with the FDC.

Disclaimer: this article represents the views of a hyperacusis patient, not necessarily those of Hyperacusis Central.

References

Clavier, O. H., Dietz, A. J., Wilbur, J. C., Zechmann, E. L., & Murphy, W. J. (2012, September 1). Measurements of bone-conducted impulse noise from weapons using a head simulator. The Journal of the Acoustical Society of America, 132(3), 2014. https://doi.org/10.1121/1.4755453

Dietz, A. J., Audette, W. E., Wilbur, J. C., & Passow, C. H. (2011, October 1). Protecting beyond the bone-conduction limit. The Journal of the Acoustical Society of America, 130(4), 2468. https://doi.org/10.1121/1.3654910

Wilbur, J. C.,  Allen, L., Audette, W., Passow, C., VanMalden, J., Arsenault, J., Hamilton, J., Gould, K., Lei, T., Farnese, J., Pollock, S., & Kline-Schoder, R. (2023, October 1). Protecting beyond the bone-conduction limit: Lessons learned developing and fielding a passive Hearing Protection Helmet. The Journal of the Acoustical Society of America, 154(4), A348. https://doi.org/10.1121/10.0023757

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