AOPA Pilot Magazine - October 2021 - 98

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The chart shows the relative
attenuation of the headsets at eight
different points across the frequency
spectrum. On the y-axis is the relative
level of the oscillator compared to my
base hearing, so the further down (lower)
the value on the graph, the more effective
at eliminating noise the headset is at that
frequency.
The data indicates that a passive
headset behaves a lot like foamies do,
with a minor amount of discrepancy in
the higher frequencies. Sound waves,
just like radio waves, microwaves, or
even visible light all have a wavelength,
which is the distance it takes a sound
wave to complete one full cycle. The
wavelengths of higher frequencies are
often magnitudes shorter than lower
frequencies, which means we can
construct a physical barrier (either
a wall of tight foam or a rigid, tight
sealing shell) that will prevent the weak
sound waves from penetrating. Lower
frequencies, however, have much longer
wavelengths and the physical barriers
are much less effective.
While the ANR provides comparable
protection in the middle and upper
frequencies, it really earns its salt in the
low/low mid frequency ranges, providing
much more noise protection than any of
the other models. If you've worn ANR
in a cockpit before, this probably makes
98
AOPA PILOT / October 2021
the active headset with ANR turned off
versus the passive headset. This is another
common point in the FBO debate-My
active headset with ANR turned off works
just as well as a passive headset-but the
data doesn't support this argument. We
see much more attenuation in the passive
headset because of its design. The passive
headset features rigid sound cups, tighter
sealing rings, and more clamp against the
head, which, as we've already discussed,
form a physical barrier between your
ears and the noise. The active design, by
comparison, compromises some of the
structural integrity used for passive noise
reduction in favor of weight reduction and
user comfort. While an active headset with
ANR disengaged is better than nothing, it's
certainly not favorable in the long term.
The data, while interesting to people
like me, confirms what most pilots who've
flown with active headsets can already tell
you. ANR is a night and day difference
over the protection benefits of a passive
headset, and you really want to carry
spare batteries, because if your ANR dies
in flight, it's going to get a lot louder fast.
The sticker price of a good ANR headset
can cause jaws to drop, but when you
consider the risks of long-term noiseinduced
hearing loss on your ability to fly,
the investment more than pays for itself.
Joshua Boatman is a private pilot and live
sound engineer living in Tulsa, Oklahoma.
a robust design, tight fitting ear cups,
solid surfaces, and absorptive earcup
material which reflect and block sound
from entering the ear cups. Active
headsets, by comparison, rely on a
microphone outside of the headset and
a bit of audio magic and math to actively
cancel sounds in the ear cup. An active
headset with the ANR turned off works
like a (very expensive) passive headset.
sense to you. Once you turn on the noise
reduction, the engine and exhaust noise
are decreased significantly. Although
humans are most susceptible to hearing
damage in the mid/high frequency
ranges, hearing damage can occur in
lower frequency sounds as well, and for
long-term exposure in the cockpit, ANR
can help mitigate those risks.
Another noteworthy comparison is
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AOPA Pilot Magazine - October 2021

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