Plane & Pilot
Tuesday, August 25, 2009

Beyerdynamic HS 600 DANR Headset


Advanced noise reduction from Germany



Beyerdynamic’s HS 600 DANR offers 40 decibels of ambient noise attenuation, which combines both passive and active modes.
There still are a few older pilots who fly without headsets—and most have hearing damage as a direct result. For the rest of us, a decent headset is a key piece of safety equipment. Until just a few years ago, all headsets were passive, blocking out sound by clamping a small pair of cushioned speakers against the pilot’s head. This works, but getting good results requires a heavy headset and high clamping pressure, which can be uncomfortable. In the 1980s, another option became available: electronic noise-reduction headsets. They’re usually lighter—and, thus, more comfortable, especially on long flights—but less effective than conventional headsets when the noise reduction is turned off. Turn on the noise reduction, though, and engine noise drops dramatically. This happens because inside each earpiece is a tiny microphone that captures ambient noise, plus electronics that attempt to cancel that noise out.

Beyerdyamic, a German company with an 85-year history in designing and engineering audio products, has recently updated the HS 600 DANR (digital active noise reduction) aviation headset with its “version 2.0” advanced noise-reduction features. The company claims 40 decibels (dB) of “ambient noise attenuation” (combining both passive and active modes), compared with 21 to 27 dB for most passive headsets.

To understand that, you need to know that a decibel is a logarithmic measurement of sound pressure. Add 20 dB and you’ve increased the pressure by a factor of 10. That’s important because too much pressure can damage your ears. According to an FAA safety brochure, continuous exposure to sound levels of 90 dB or higher can produce permanent hearing loss. Average noise level in single-engine piston cockpits ranges from 70 to 90 dB, which is uncomfortably close to the limit. Conventional passive headsets cut this by 19 to 27 dB, which certainly helps, but they’re most effective at cutting high-frequency noise—and how well they work depends on how good a seal the earphone cushions provide against your head. Those of us who wear eyeglasses never get a perfect seal, so we tend to get less noise reduction. Even with a perfect seal, there’s still a low-frequency rumble that’s similar in pitch to human speech, so you still may have trouble understanding your copilot, passengers or ATC when it’s calling “traffic alert.” Electronic noise reduction filters out low-frequency noise and makes it easier to hear the intercom and radio. Most vendors who offer electronic noise reduction claim around 20 dB of additional noise reduction over and above the passive reduction offered by the earphone seal.




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