Headsets: Choosing The Right Tool

The Right Tool
Have you ever wondered why there are so many different kinds of hammers? Home improvement stores have rows and rows of hammers, although to most people they look identical and do the same thing: deliver an impact to an object. Why would there be some 20 variations of this basic tool? The answer is because each hammer has enough of a variation---however slight---to make it a better tool for different jobs. A roofing hammer is terrible for gingerly breaking up the small rocks a geologist might find. A ball peen hammer is great for shaping rivets; a framing hammer is lousy. The old mechanic's adage that there's only one tool for the job is true both for hammers and headsets.

While surfing through the vast sea of Internet aviation forums, I came across a lively discussion about headsets. One poster was adamant that, in his airplane, only BRAND X headset worked well, given the high noise level in his cockpit. Poster #2 countered that BRAND X had never worked for him---in the same type of airplane---and that BRAND Y was the real answer. A few heated posts later, a third pilot jumped in---again with a similar airplane---and countered that BRAND X and Y were both overpriced junk, and that he had discovered BRAND Z, and that was the only headset that worked.

The forum exchange mirrored what I've discovered in aviation when it comes to headsets: They're as personal as underwear. To increase the chances of selecting the right headset, pilots need to come to the buying table with a bit of savvy.

The Noise Capsule
It must be understood that general aircraft cockpits are torture chambers for our ears. They are---without apology---capsules of deafness by design. Think of that huge chunk of metal under the cowl, hosting explosions of fuel every millisecond, just 36 inches from your head, and that heavy mass spinning at the end of the crankshaft, beating the air some 5,000 times per minute with enough force to propel a ton of metal through the air at over a hundred miles per hour.

Consider that same heave of wind relentlessly pummeling the thin aluminum sheet surrounding you. It's not just the volume of the noise, it's the fact that the noise is focused on the same frequencies for hours and hours. Imagine somebody unceasingly pounding a piano's low-C key next to your eardrum day after day. These are the nightmares that keep hearing doctors in business.

Now, add vibration to the aural onslaught. Vibration noise creates a low-frequency bleat that's pure hell on your cilia---the tiny, hair-like cells inside your inner ear that vibrate in reaction to sound, and sway back and forth like a field of Kansas wheat in a breeze. Cilia are resilient; when they get hit by loud sounds, they bend and spring back, warning you with ringing that lasts hours or days. But you only have a fixed number of cilia. Abuse them enough and they won't spring back. That means permanent hearing loss. You can't regenerate cilia---ever.

Scientists tell us that hearing damage starts to happen at around 85 dB (a decibel is the unit to measure sound intensity). Our GA cockpits subject us to constant noise at and above 95 dB. As a comparison, an iPod at full volume plays at about 120 dB---the same sound pressure as sand blasting. And a human whisper measures about 30 dB. Exposure to 120 dB causes permanent hearing damage in just seven minutes. In our cockpits, ears begin to suffer serious damage in just two hours.

To prevent hearing damage, the aviation headset was introduced around 1975, and it's what we use today, essentially unchanged. There were some earlier variations of headsets, and in World War II, some pilots wore crude "radio sets" made by Western Electric, but the modern-type headset has only been around for about 40 years.

The ANR Versus Passive Myth
Today, we have two kinds of noise attenuation in headsets: passive and active. Active noise reduction is referred to as ANR. It's important to understand the differences between the two, and why the myth persists that ANR is better because it's more modern.

Hardly "new" technology, ANR was around in the 1950s in helicopters, originating from a patent by inventor, Paul Leug, in 1934. Bose introduced ANR headsets to general aviation in 1986. Since then, the technology has remained basically unchanged.

ANR headsets analyze the sounds hitting the ear using tiny microphones. When the ANR circuitry senses unwanted noise (fixed frequencies based on an algorithm), the headset's speaker emits a sound wave that matches the noise, but with an inverted phase to it, cancelling it out. The effect is known as "phase cancellation." ANR is mostly effective against low-frequency noise, and not so good at blocking high frequencies.

Passive noise reduction headsets (also called PNR) use only physical means to block unwanted noise, including barriers, absorption materials and sound damping. The ear cups act as both a sound enclosure and a barrier to noise by blocking its path and sound energy. Different kinds of foam and other absorbent materials also dissipate the energy of the offending noise. Gel seals, material coatings and headset hardware further act to dampen the travel of sound energy. The net effect is that all sound is attenuated (reduced) evenly by stopping it from reaching the ear.

Open cockpits and aircraft with high- performance engines present problems for the ANR headset. First, the noise in those cockpits comes from a lot of different sources and usually includes a lot of high-frequency stuff from the slipstream and prop. Second, the sound varies wildly---especially in open cockpits---depending on how the pilot moves his or her head, how the prop is set and where the throttle is. In those cases, ANR is wrong for the job.

Passive headsets are neither better nor worse than ANR, they're just different. If you're experiencing issues with your communications, the wrong headset could be at the center of your problem. ANR has been a godsend for many pilots, but in the wrong cockpit, it can be disastrous. Again, it's about choosing the right tool.

Alternatives
In recent years, some interesting alternatives to the traditional headset have emerged. The most promising of those is the in-ear headset. In-ears do away with all the clamping mechanisms, weight and ear cups of standard headsets. A featherlight wire goes around the pilot's head and supports the condenser microphone. These headsets take passive attenuation to new heights by fitting the speakers into tiny, earbud-like transducers that insert directly into the ear canal with foam plugs. With the sound pointing directly at your eardrum while the plugs block out everything else, they're hyper-efficient. They require no battery, and come close to doubling the attenuation of traditional headsets, with ratings upward of 45 dB! Weighing less than an ounce, they can be worn for hours.

Leaders in the in-ear field include Clarity Aloft, Lightspeed, Quiet Technologies and Swiss company Phonak with their FreeCom series. The disadvantage of in-ear headsets has always been their cost. However, since Quiet Technologies introduced their excellent-sounding "Halo" for $359, thousands of pilots are discovering the freedom of the in-ear design. For people who can't tolerate anything inside their ear, custom ear molds are an option, because they sit more on the ear instead of in it, and work well with these types of headsets.

A recent trend is the use of earbuds in the cockpit. Earbuds are those tiny speakers you use with MP3 players and tablets. By adding a 3.5mm to ¼-inch adapter and plugging them into the airplane's "PHONE" jack, they can be used in place of the headset's speakers. The headset is worn over the earbuds for its microphone and for added noise attenuation. Pilots should know that the impedance of earbud speakers is typically 16 Ohms, which is a big difference from the 150-300 Ohm speakers your aircraft's radio is designed to drive. The difference could create volume issues for passengers, or pull too much current, so contact your intercom manufacturer and ask about using earbuds with it.

New Directions
True wireless headsets are the Next Big Thing, although the technology has remained a bit elusive. A few companies have tried, though their offerings weren't quite mature enough to warrant widespread attention. The EQ-1 wireless headset from EQ-1 Wireless Communications is turning heads, especially with the addition of their new "EQ-Link" adapter that can make any standard aviation headset wireless. Wireless will finally free us from cords and tangles.

Bluetooth is still a hot trend, and an innovator in this area is Pilot Communications. Their BluLink wireless adapter has been getting rave reviews since it was introduced, and is the only device of its kind. BluLink enables you to use your Bluetooth cell phone or any music source wirelessly in the cockpit. You can use your existing headset with BluLink. Pilot USA combined the BluLink with their PA-2170 headset, creating the only passive headset on the market with Bluetooth communications built into it. The company has also been getting attention from the open-cockpit, aerobatic and sport market with their PA9-EHN "extra- high-noise" microphone, which makes a dramatic difference in intelligibility in noisy cockpits.

Meanwhile, newcomer Squawk Shoppe has created a niche of their own with custom-graphic and wild-design headsets for the more adventurous pilot. Their "Nimbo" (PNR) and "Arcus" (ANR) lines of aviation headsets feature bold-color camouflage patterns, animal prints, flags, textures and even pin-up girl designs. From a graphical standpoint, they're completely different from anything on the market. The company also offers a nifty USB adapter to allow using your headset with PC programs like flight simulators, Skype or others.

One of the coolest iPad apps to come along is "FlightLink," Lightspeed's new cockpit voice recorder application. Free from iTunes, FlightLink lets you record all your cockpit audio in real time onto your iPhone or iPad. For now, it only works with the latest-version Lightspeed, Zulu .2, but we're hoping it expands to other headsets. The app records audio in Apple's proprietary .caf format---which can make for large files---that can be edited in many audio programs. It's a fun and easy way to record cockpit audio without a maze of wires and adapters.

Personal Touch
Give a thousand people sapphires and one will complain that it's not an emerald. That's the nature of our humanity. What fits one person will feel torturous to the next. It's partly physiology and partly perception. For headset buyers, it means that personal comfort should be right up there with attenuation ratings. Manufacturers have realized this and almost all of them offer generous "try out" periods to allow pilots to really get to know their headsets.

Having tried bushels of headsets myself, I can attest to the fact that they're as different as we're unique. Carefully evaluate your own cockpit environment, the length of your trips, and your personal physiology, since not all ears are created equal. Don't go by the sales pitch, and never make a purchase decision on price alone. Even though headsets all seem awfully similar, like hammers, there's one out there that's just the right one for the job, and for you.