Originally published May 1995
What's that you say? You don't have a David Clark Noise Canceling headset? Can't seem to make the tradeoff between hearing protection and, say...10 or 12 flying hours? Well, neither could I until I noticed an ad for the above mentioned device. Long story short; this little jewel will, for the paltry sum of $139 and a little brow sweat, turn you plain ol' David Clarks (or clone thereof) into an active noise canceling headset! Given the huge disparity between this price and that of a competitive active headset, I was a little skeptical of performance, but since the technology seemed reasonable and the ad didn't emanate from a third-world country, I offered up my Visa number. Fully six weeks later (apparently I wasn't the only person to notice the ad), I received a small box from Headsets, Inc. (catchy name, eh?) of Amarillo, Texas. The box contained two dual-speaker assemblies with attached circuit boards, a battery box, and some multi-conductor cable assemblies. Quality of construction was quite good with modern surface mount technology used in the 1" by 2" circuit boards on each earcup unit. I was a little disappointed with the battery case, which looked very similar to a flimsy 35mm slide storage box and was designed to hold the primary 9v battery and a spare. Casting the rather detailed schematics aside (real men don't need instructions) I proceeded to dissect my trusty headset. Though not a true David Clark, this ex-military (honorably discharged) unit bears a striking resemblance to the green domes. In about at hour I had, a.) drilled three small holes in the domes to accommodate the crossover and power cable; b.) Installed said wires; c.) replaced the existing speakers with the new units; and d.) reassembled the headset. Much to my surprise, the thing worked first-time out! The units add about 3 oz to the headset, along with a three foot power cable to connect to the battery box. A cigarette lighter or direct wire option is also available.
And how does it work? What, can't hear you...(just kidding). Turning on the nine volt power source in a reasonably quiet environment produces a dramatic "hush" accompanied by a barely audible hiss. Turning it on in the office of my usual flying machine, a 235 hp Pawnee tow truck causes the usually raucous roar to subside to a pleasantly low rumble. Though I am pitifully short of quantitative data (Headsets, Inc. claims a 22 db reduction), I can qualitatively say the effect is roughly equivalent to wearing foam ear plugs under the non-active headset. I should also note that this headset has been liberally modified with Oregon Aero comfort and noise deadening products and is probably providing 26-28 db protection without electronic help. Why not just buy $2.00 worth of EAR plugs, you say? Well, for one thing, the clarity of radio transmissions is incredible since you don't have to overcome the sound deadening effect of the foam plugs with high audio gain. For another, I love gadgets...'nuff said? Bear in mind that the units are designed to reduce noise in the 20-700 Hz range, which is where your common early-20th century technology prop/motor combination shouts the loudest. Higher pitched noises, like those from leaky windows/doors, whining kids, or terrified spouses come through loud and clear---Pietenpol and JP-8 burners take note. I've got about 12 hours on the units at this writing and am still quite satisfied. The original battery gave out at about 10 hours, though a quick change to the backup saved an otherwise noisy flight.
If you are interested in further details or would like a demo, feel free to contact me through the chapter address list. If I've already sold you, contact Headsets, Inc. at (806) 373-9515 and I'm sure they would be glad to accommodate you.
Contents of The Leading Edge and these web pages are the viewpoints of the authors. No claim is made and no liability is assumed, expressed or implied as to the technical accuracy or safety of the material presented. The viewpoints expressed are not necessarily those of Chapter 1000 or the Experimental Aircraft Association.
Revised -- 22 February 1997