Can You Hear Me Now?
By Rob Seaman
My first helicopter flight experience was a ride in a Bell 47 that, upon reflection, hadn’t seen much improvement or updating since its days flying for the military.
By Rob Seaman
My first helicopter flight experience was a ride in a Bell 47 that, upon reflection, hadn’t seen much improvement or updating since its days flying for the military. No headset was offered or available, and while it was a thrill, I still recall the ringing in my ears I had for quite a while afterwards.
|Buying a headset or helmet involves consideration of uses, flexibility for varied aircraft and avionics systems, fit and comfort, along with other factors. (Photo courtesy of Gentex)
Years later, I had another opportunity to fly from the cockpit of a Harvard. The owner handed me an old leather flight helmet with antiquated, ill-fitting earpieces and a microphone that worked occasionally. As anyone who has done this knows, hours after you land, you can still hear the engine noise in the back of your head. That led to the purchase of my first headset – a top-of-the-line David Clark model with noise-cancelling microphone. A while later, after watching a colleague flip on his back while landing but walk away unscathed because of his helmet, a war surplus “bone dome” was in the offing.
Custom fit helmets were not in the budget for most of us at that time and not many original equipment manufacturers (OEMs) were making equipment for the civilian market yet. Older helmets tended not to fit properly and they always left you with a sore neck. Nonetheless, it made passengers and pilots safe and communication in the cabin was adequate.
Fortunately, technology and design acumen have rendered a totally different story today. Buying a headset or helmet involves consideration of uses, flexibility for varied aircraft and avionics systems, fit and comfort along with other factors. Options abound with easy access through OEMs and dealer networks.
Stalwarts in the headset market include Bose, David Clark, Lightspeed and Sennheiser. There is also an exciting newcomer – the Squawk Shoppe. For helmets, OEMs of choice include Gentex, MSA Gallet and Alpha Eagle. In most cases, choosing a helmet is step 1 in the process and a headset of choice is incorporated into the package. Some headset OEMs have preferred relationships with helmet manufacturers, but an avionics dealer can help figure out the combination of equipment and fit. This does make shopping online more difficult, but think of it as a made-to measure suit – a little tailoring always gets a better look and feel in the end.
In terms of cost, a top-of-the-line helmet will run in the $1,500 to $2,000 range but with this comes quality, reliability and top service for many years to come. Headsets alone start a little north of $125 for a very basic model and run upwards of above $1,100 for top-notch equipment. As with anything, you can set purchase requirements to just get by, or take the matter of safety and hearing protection seriously and invest wisely.
What Constitutes a Great Headset?
Mitchell (Mitch) Bouton III is vice-president and general manager of headset newcomer, the Squawk Shoppe LLC. When asked to describe top features in a great headset, Bouton quickly points out that it has to be lightweight and offer 25 decibels of sound reduction or better (25 decibels is the military benchmark for sound reduction). “This is where you want the most bang for your buck,” he says. “Typically, the higher the weight, the better the sound reduction. However, you must consider anything over 16 ounces to be of concern since you might be wearing this device for several hours.”
Next is good sound attenuation, notes Bouton. “After protecting your hearing, the greatest value of a headset is in allowing you to communicate more clearly and easily both inside the cockpit (through the use of an intercom) and outside the cockpit when talking to air traffic control, flight service or other aircraft.”
After this come comfort levels. “This is of considerable importance when wearing anything, especially on your head. Just keep in mind, that most headsets sacrifice sound reduction in order to achieve comfort. Others will simply add a thicker or more robust head-pad to offer more comfort in order to offer better sound reduction. This delicate balance should weigh heavily in your decision for a quality product that won’t be a burden to your comfort. Nothing is more distracting than a pounding headache from a headset that clamps too tightly.”
David Dunlap, director of Sennheiser Aviation, advises that in order to make its headsets flexible in fit and comfort, the company has incorporated a variety of user-adjustable features. For example, the S1 Digital headset includes:
- Headband tension adjustment: This allows the pilot to make the headset tighter or looser up to 30 per cent.
- Eyeglass comfort zones: The ear pads of the S1 family of headsets include softer (less dense) foam in the region of the ear pad where eyeglasses pass through; this reduces the “squeeze” on the glasses, and provides a better acoustic seal around the temples of the glasses.
- Headband padding: The centre-offset padding of the S1 family of headsets prevents “hot spots” from forming on the most sensitive centre-line of the skull. These pads are also easily replaced with thicker padding or sheep-skin padding as desired.
The weight of a headset will dramatically affect comfort level, especially over long flights. As both Bouton and Dunlap suggest, heavier headsets can strain your neck and shoulders while the lightweight ones may sacrifice sound attenuation and reduction. Bouton maintains that most headset manufacturers offer single or double cotton head-pads. “Either version is going to give you what you need for comfort. It really depends on your preference. Finding the right balance between weight, clamping power, adjustability, padding comfort and db reduction is very important.”
The rest of Bouton’s list includes boom selection, added features such as MP3, radio, iPod, iPad and Blue-tooth, warranties and safety factors. The last thing is a specialty of the Squawk Shoppe – customization such as colour choice, graphics and logos.
So how much noise cancellation can you expect through a headset? The noise-cancellation value or an active noise reduction (ANR) can be established in a number of different ways. Dunlap advises that for passive attenuation, the industry standard is the Noise Reduction Rating (NRR). His firm’s S1 family of headsets achieves an NRR of approximately 23 decibels, a very respectable passive noise-reduction level for a passive headset, let alone an active noise reduction headset.
“To establish the performance of the S1 Digital ANR, Sennheiser used the psycho-acoustic standard measure of loudness,” says Dunlap. “Loudness is more complex to calculate: a method is provided by the standard DIN 45631/ISO 532. Loudness is expressed in “sone.” Measuring loudness accounts for the appropriate noise (aircraft cockpit noise) and measures the perceived loudness received by the pilot/wearer of the hearing protection. In comparative measurements, the S1 Digital performed the best against its rivals due to the digital adaptive nature of the ANR algorithm.
Meshing Top Headsets With Helmets
As John A. Winship, Canadian marketing manager for the Gentex Corporation points out, an aircrew helmet provides some level of protection to the wearer while serving as a mounting platform for ancillary devices such as communications components and hearing protection. It also provides facial protection, solar glare and laser light protection for the eyes, and mission enhancement devices such as Night Vision Goggles (NVGs) and electronic displays.
|HEADPHONES TOP: Bose continues to be a stalwart in the headset market. (Photo courtesy of Bose)
MIDDLE: An exciting addition to the helmet manufacturing scene is Squawk Shoppe's custom gear. (Photo courtesy of Squawk Shoppe)
BOTTOM: The S1 Digital headset includes a headband tension adjustment that allows a pilot to make the headset tighter or
looser by up to 30 per cent. (Photo courtesy of Sennheiser)
There are fundamentally two types of helmets – fixed-wing and helicopter. Helicopters typically being noisier and having longer mission duration, demand higher levels of noise protection. Observations and statistics from many military accidents have been amassed to support the current design attributes of aircrew helmets.
“It usually takes an interactive process between the individual aircrew and the helmet provider to determine what combination of factors will make the best solution for a helmet in any given case,” says Winship. “As a result, there are very many possible helmet configurations that might be offered.”
When a customer first goes out looking for a headset or helmet – or a combination of the two – there are some basic screening or determining questions that need to be asked to determine the right product. According to Dunlap, “We ask first what aircraft the individual flies. This gives us the information of approximate noise level and probable interface. Then, we proceed to ask about how many hours they fly, and verify the interface to the aircraft by asking which headset they currently use. In talking with individual pilots, we can also learn about their comfort issues with their current headset, if any, and recommend the right headset for them.”
The process is similar at Gentex – determining aircraft type is the first priority. “This will drive what their requirements are for protection, communication, and so forth,” notes Winship. “The requirements for a helicopter helmet are very different from [those of] fixed-wing aircraft: level of hearing protection, protection from multiple impacts and such are all issues differentiating helicopter from fixed wing. Helmets are specifically designed and tested to function in these different flight environments. Civilian aircrew are the beneficiaries of extensive military research and development efforts where life support equipment items involved in accidents and serious incidents are studied to better understand how they functioned during the accident sequence and what needs to be improved. The results of such studies are enshrined in military specifications and standards that are used to design and test helmets.”
Helmet Weight and Comfort
Winship advises that considerable effort and resources have been invested in the study of weight and comfort. Back and neck injuries are common in helicopter aircrew. Some researchers maintain that exercises to strengthen neck muscles can help prevent injuries, while other experts say stronger neck muscles can contribute to underlying bone injuries due to added stress on the spine from tighter muscles. “Suffice it to say, from a helmet perspective, the lighter the helmet, the better it would seem to be,” he says.
Helmets today are designed so that the helmeted head has the same centre of gravity as the bare head. There are questions about devices mounted on helmets. For example, an NVG mounted on the front of the helmet switches the centre of gravity forward. Some aircrews elect to use counterweights attached to the rear of the helmet to correct this. While this technique works in the vertically erect position, what occurs when the aircrew leans forward? In this case, there is even more strain on the neck. Some aircrews simply choose not to wear counter-weights, thereby reducing the overall head-borne weight although changing the centre of gravity. As Winship notes, there is no simple answer and room for more research to find appropriate solutions to these issues. The bottom line is, careful fitting and maintenance is necessary to ensure a proper fit as keeping the helmet properly situated on the head will minimize injuries from constant shifts in one’s centre of gravity.
A correctly fitted helmet not only provides a comfortable and stable fit, but it also protects a pilot during a mishap. According to Winship, insurance companies are recognizing this and may offer discounted rates for operators; it also reduces liability risks.
Gentex reports that for its rotary-wing product line, the HGU-56/P weighs less than 1.4 kilograms with a dual visor kit attached. The midrange SPH-5 weighs in at less than 1.48 kg.
Making the Purchase
While easy and convenient, online shopping for helmets does present challenges for getting the right equipment. As one can see from the helmet considerations noted, buying online is possible but not the best idea given all the variables. The best plan is to find a dealer and work through them.
Purchasing headsets is a different story, however. As Dunlap points out, online buyers (who come to them primarily through their dealer network), try to provide sufficient descriptive information and photographs of their needs to allow them to make the right choice. To ensure the right choice is made, every Sennheiser headset sold in North America comes with a 30-day money-back guarantee. Before you make a purchase, it’s critical that there’s favourable return or exchange policy if the fit just isn’t right.
Buy or Borrow?
Some operators may maintain that a headset or helmet should stay with the aircraft, but a growing number of pilots consider helmets and headsets standard parts of their personal flight kit. While a pooling of helmets does occur in some organizations, it’s not recommended. Helmet stability may be an issue and most pilots will take better care of a helmet that they are assigned to (or own) as opposed to one they are sharing with others. “Its somewhat akin to organizations providing safety footwear to their workers – they don’t ask that the footwear be shared from one worker to another,” notes Winship. “The same principle should apply with any item worn ‘next-to-skin’.”
When selecting a helmet the costs are significant and the process involved, but once this valuable safety and communications tool is in hand, it will be yours to keep and manage for some time. As a pilot, you will always be assured of a quality, safety fit and have the tools of your trade in good repair. Plus, it beats the heck out of constantly saying “eh?” as you try to understand others after having your hearing irreparably damaged.