April 1, 2001
By Elizabeth A Tennyson
One of the first pieces of aviation gear most students consider purchasing is a headset. While you may be able to rent or borrow one from your flight school, you also may discover that the school's equipment is a little too well-worn or that headsets are sometimes unavailable when you need them. Even if your school is amply supplied with high-quality gear, many FBOs that are happy to loan or rent to students are loathe to keep handing out headsets once those students become certificated pilots. Either way, before you know it you'll be in the market for a headset of your own.
Selecting a headset can be confusing. Perhaps you'll try, as I did, asking your instructor and other pilots around the flight school for recommendations. If you do, you'll quickly discover that choosing a headset is a little like choosing a carï¿½the flashy, red two-seater your neighbor just bought may not be a comfortable fit for your next weekend trip with three kids and the family dog.
Since choosing the right headset is such a personal decision, it's a good idea to think about what matters most to you before you start to shop. Of course, you'll need a starting point. Just what are your options, and what factors should you consider before investing in a new headset?
One of the first factors to look at is whether or not you want an active noise reduction (ANR) headset (also called active noise cancellation, or ANC), or a more traditional passive noise reduction model. Active noise reduction is a relatively new technology that is especially effective at reducing low frequency noise, such as the engine and propeller noise in a light aircraft.
ANR was first conceived in the 1930s and had started showing up in science fiction stories by the 1950s, but it was the 1970s before mainstream scientists began to investigate the possibility seriously. ANR technology didn't become a reality in general aviation until the 1990s.
Here's how it works: A tiny microphone, typically placed in the earcup of a headset, picks up noise inside the earcup. That information is transmitted to the headset's electronics, which drive a speaker, also inside the earcup, to produce a noise that is the exact mirror image of the original noise. In other words the "trough" of one sound wave (the noise caused by the propeller) corresponds to the "crest" of another (the "antinoise" created by the headset). When the sound waves collide, they cancel each other out; so what you hear is the sweet sound of silence.
That's not to say that an ANR headset will leave you unable to hear the important things going on around youï¿½like air traffic controller instructions and the hum of the engine that lets you know everything is as it should be. ANR works most effectively on low-frequency noise. (This is the kind of noise that causes permanent hearing loss across all frequencies, if experienced over a long period of time.) ANR does very little to affect the relatively higher frequencies of, for example, voices. In addition, it really only works well for tonal noisesï¿½those sounds containing a very limited number of frequencies, such as propeller noise; so you still hear broadband, mixed frequency sounds, such as the wind flowing over the airframe. You can also tell when a sound changes. So, if the rhythmic pulse of the propeller is altered by the addition or loss of power, your ears will tell you about it.
Passive noise control is much more simple. It works by muffling noise, as when you put your hands over your ears. Passive headsets use thick earpads, often of gel or foam, to create a seal around each ear. Clamping action keeps the seal tight against your head, but sunglasses and even hair can get between the ear seals and the side of your face, significantly reducing the effectiveness of passive noise reduction.
Since the primary reason for wearing a headset is to protect your hearing, you need to know how well any headset reduces the amount of noise reaching your ears. Both passive and active noise reduction headsets come with a noise reduction rating or NRR. The Environmental Protection Agency requires headset manufacturers to test their products and determine by how much they reduce noise. This figure is then reported as an NRR, given in decibels (dB). An NRR of 26 dB tells you that a headset reduces the amount of noise reaching your ears by 26 dB. Active noise reduction headsets may give two figuresï¿½one for the noise reduction when the electronics are turned on and one for when they are not.
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. To make sure that a headset is helping, not hurting, the quality of your communications, you need to know a little about its microphone and speakers.
There are three primary types of microphonesï¿½electret, carbon, and dynamic. Electret microphones are the most popular for aviation use. They are smaller and lighter than other microphone elements and work by placing a charged, flexible diaphragm a given distance from a fixed plate. Sound waves created by speaking into the microphone cause the diaphragm to vibrate, changing the distance between the diaphragm and the plate. Those changes are translated into electrical signals and transmitted.
Carbon microphones are the simplest and least expensive. In carbon mics, the movement of a diaphragm is transmitted to carbon granules inside a small container connected to the diaphragm. As sound waves strike the diaphragm, the carbon granules move. The resulting fluctuations in the current running through the system are then amplified and transmitted.
Dynamic microphones form a middle ground in terms of cost and sophistication. In these microphones, a coil of wire is connected to the diaphragm, which is in a strong magnetic field. Sound waves moving the diaphragm and coil generate an electrical signal that varies in voltage with the amplitude and frequency of the sound waves. Because dynamic mics use a magnetic field, they are susceptible to electromagnetic interference, which can garble transmissions. Dynamic mics for aviation use are carefully shielded to minimize the chances of such interference.
Much is made of noise canceling microphones and with good reasonï¿½the less background noise cluttering up your transmissions, the better. Any type of microphone can be designed to help cancel noise, but electret microphones are generally considered the most effective when it comes to noise cancellation.
Here's how it works: When sound waves, including the undesirable sound waves we call noise, reach the diaphragm of a microphone, those sounds are transmitted. But, if sound waves reach both the front and back of the diaphragm simultaneously, the diaphragm doesn't move, effectively canceling out the sound. (Picture you and a friend standing on opposite sides of a partially open door. If you both push on the door at the same time, with the same amount of force, it won't move.) Noise canceling mics have openings that channel ambient noise to both sides of the diaphragm. When you speak into the microphone, however, the sound waves from your voice hit only one side of the diaphragm, allowing it to flex. (Let go of that door as your friend continues to push and watch it swing open. Depending on how much you like your friend, you might want to warn him first.)
Headset speakers are important, too. The higher the quality the speaker, the easier it will be for you to make out that speed-of-light controller talk. Both dynamic and magnetic forms of sound reproduction work well in aircraft. In either case, the basic principle is the same. When you are receiving a signal through your headset, small voltage changes cause diaphragms in the earcups to vibrate. Your brain perceives these vibrations as recognizable sounds.
Unlike the headsets you use to listen to music, aircraft headsets must be able to cope with changes in pressure caused by changes in altitude. The FAA requires that the diaphragms for headphone speakers be properly ventilated so that they don't implode or explode as a result of changing pressure. They also must withstand extremes of temperature and humidity. As a result, expect your aviation headset to use diaphragms of metal or Mylar, rather than the paper diaphragms common in home stereo equipment.
Flight lessons typically last one to two hours, but cross-country trips can take much longer. It's those long trips you need to keep in mind when you look at the comfort of a headset. After all, nothing is more distracting than a pounding headache from a headset that clamps too tightly. Clamping power isn't the only factor that plays into comfort. You'll also want to consider weight, padding, adjustability, and materials.
How tightly a headset clamps against your head helps determine how well it keeps out noise. This is especially true for passive noise reduction models. But a headset that pushes too tightly will leave you with a headache. Because everyone is different, the only way to know if a headset will clamp too tightly or not tightly enough is to try it out.
The weight of a headset can dramatically affect your comfort level, especially over time. Heavier headsets can strain your neck and shoulders. Most manufacturers list the weight of their headsets in the product specifications so you can compare. ANR headsets have traditionally required a separate power source for the noise-canceling electronics. That typically means a battery pack, although one new model uses the microphone bias power instead of a battery to energize the noise-canceling electronics. A few models place the batteries inside the earcups, which can add to the weight pushing down on your head. Most place the batteries somewhere along the wires leading to the microphone and speaker jacks, which can be a little cumbersome. The size and placement of batteries for ANR headsets is an important consideration.
The type and amount of padding in a headset also can make a difference. Padding under the headband and around the ears is most important, but some headsets can be comfortable for long periods with minimal padding. Again, this is something you'll have to test for yourself. If you are tall, keep in mind how headset padding can affect the amount of clearance between your head and the top of the cabin.
All headsets adjust to some degree. Most have adjustable headbands to help you position the ear seals comfortably. But most headsets were originally designed and sized with men in mind. Petite women will want to be sure to choose a headset with a band that adjusts small enough to give them a proper fit. The microphone boom on most headsets also is adjustable. Some pilots prefer a fully adjustable boom so that they can position the microphone with great precision. Others are just as comfortable with a hinged boom that typically bends at one or two places along its length. In addition, some booms swing all the way around, allowing you to wear the mic on the left or right side, depending on whether you are sitting in the left or right seat. Others are fixed for left-side use only. Choosing the right kind of boom is important because you will be much less comfortableï¿½and much more distractedï¿½if you can't get the microphone to stay where you need it.
Finally, the materials that go into your headset can affect your comfort. Metal headsets tend to be a little heavier than plastic ones but may be more adjustable. Gel padding tends to be a little heavier than foam, but many pilots believe it provides somewhat better cushioning. Vinyl-covered surfaces, especially around the earseals, can be uncomfortably sweaty in hot weather, but knit or cotton covers may not give you as good a seal. Keep all of these things in mind as you shop.
In addition to the basics, most headsets come with one or more additional features. Before buying you should think about how significant these features are to you.
Some headsets come with a carrying case to protect your investment. While this may save you a little money on the purchase, you can readily buy headset cases separately and your flight bag may have a headset compartment as well, so this is more of a bonus than a necessity.
Many headsets offer volume controls. Some models have a single knob on one earcup that controls volume for the unit as a whole. Others offer separate volume adjustments for each ear.
Most major headset manufacturers offer a warranty on their products. The warrantees typically range from one to five years, but a few manufacturers offer lifetime guarantees. Check the terms of a warranty to determine exactly what is and is not covered.
Other features you are likely to encounter are mono/stereo switches, shirt clips to keep cords out of your way, and microphone wind screens to minimize popping sounds.
As much as we'd all like to be able to look at the headset salesman and say, "Money is no object," that's simply not true for most of us. So it's important to choose a headset that meets your needs at a price you can afford. Headsets are available across a huge price range. The least expensive models can be had for about $90. The most expensive cost more than $1,000. While there are significant differences between what you get at these extremes, you will also find that there are many functional, reliable, and effective headsets available at all price levels.
It should come as no surprise that ANR headsets generally cost substantially more than passive noise reduction models. The good news is that prices for ANR headsets have come down dramatically since their introduction and are still falling. An entry-level ANR headset can be had for around $300 with prices, and features, going up from there. Passive noise reduction headsets can be had for under $100 with the bulk of models priced between $150 and $300.
When it comes to choosing a headset, there are a lot of decisions to make, many of them personal. Try out as many models as you can before you buy. Aviation trade shows are great places to try on all of the latest headsets and sometimes get reduced "show special" prices. Pilot shops, aviation catalogs, and the Internet are also good places to look for the headset that's right for you. Once you've found the model you want, be sure to compare prices. Some retailers actually sell headsets for less than the manufacturers, and price differences between retailers can exceed $100 on the same model, so it's worth your while to shop around.
While this is not a complete list of aviation headset manufacturers and companies that sell branded headsets, it does include many of the major brands. Talk to representatives of these companies or visit their Web sites to learn more about their products.
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