INDUSTRY AND COMMUNITY NEWS
Sennheiser S1 Headset
Advances ANR Technology
J. MAC MCCLELLAN
THE NEW SENNHEISER S1 digital headset
offers an impressive combination of
advanced digital electronic noise canceling
and passive hearing protection all with
excellent wearing comfort. The S1 is
expensive, but you get a lot of
performance and capability for the money.
Unlike some other high-end electronic
noise canceling headsets, the S1 has large
ear cups with soft cushions to rest against
the head. A full-coverage ear cup made
from dense material is the only way a headset can block noise without active electronic
noise canceling, and the S1 is very effective
in this passive mode. Batteries can quit,
and electronics may fail, but the passive
noise attenuation of a full ear cup is
To enhance the comfort and fit of its ear
cups Sennheiser made the S1 asymmetrical,
a first for aviation headsets as far as I know.
Because our ears are really mirror images of
each other they have a front and a back.
Sennheiser designed the S1 ear cups to fit
comfortably over the right and the left ear.
That means you cannot reverse the headset
so the microphone boom is always on your
left side. But the cup fit is ideal for each ear.
Sennheiser was so focused on the fit and
comfort that the cushion material in the
front center of each ear cup is softer to fit
better around the temple piece of the eyeglasses most of us wear while flying.
Sennheiser also did a total redesign of
the automatic noise canceling electronic
technology using digital instead of analog
electronics. And the NoiseGard, as
Sennheiser calls its system, tracks both noise
inside and outside the ear cup, while traditional noise canceling headsets only deal
with sound inside the cup.
As you probably know, automatic noise
canceling headsets create an “anti-noise”
sound that cancels the unwanted sound. The
anti-noise sound wave is exactly 180 degrees
out of phase with the noise. When the two
waves collide the unwanted sound is eliminated and we hear nothing—actually close to
nothing because the anti-noise can’t be absolutely perfect.
Sennheiser calls noise detected inside
the ear cup “feedback noise,” and the S1 uses
that input to cancel most noise in the lower
frequency range. The new mics mounted on
the outside of the ear cup detect what
Sennheiser calls “feedforward” sound. The
feedforward logic is most effective at canceling higher frequencies. Combining both
technologies in a single headset offers a
broad frequency range of automatic noise
canceling that is not overwhelmed by the
volume or frequency of the sound.
Because the S1 uses digital logic it maps
the sound frequency and level and develops
a strategy to cancel the noise. The traditional
analog system simply measures the noise
present and develops an anti-noise wave for
the average sound in the ear cup. The digital
circuit is especially good at eliminating
repetitive noise of the same frequency and
amplitude—such as noise created by the propeller rotating at a constant rpm, or the
shriek of a door seal leak when the airplane
is flying at a steady airspeed.
I flew with the S1 in my Baron for a little
more than 20 hours with legs as long as
three hours and 45 minutes and can say the
comfort is very good. You can adjust the
squeeze pressure, so if your head is bigger
than average, the headset is still comfortable.
And the microphone on the S1 is simply
excellent, the best I have used yet. My wife,
Stancie, who is a very harsh critic of headset
comfort and performance, pronounced the
mic the best she has heard coming through
our intercom, and also approved of the S1
comfort, a rating she has awarded only one
or two other headsets.