Being only 5 miles away from the Lightspeed headquarters, I was able to get
on of the first pair of the QFR Solo ANR headsets. These are the QUIETEST
headsets on the market, even though their ANR reduction may not be
as great as the 15K/20K/25K. Their price, at $289, is superb and frankly
stands to cannibalize sales of their
older line.
The QFR series offer over 28dB of passive noise reduction, as compared to
about 24dB for regular passive
and typical ANR sets. The ANR improves noise reduction by about 12-14dB in
the critical 50-250Hz frequency
range. The QFR series is based on the best industrial ear protector on the
market, the Howard Leight Leightning,
which offers 31dB NRR. I use this protector in the shop, and it is
fantastic, far better than the other junk you
would pick up at the Home Depot. It costs about $25, but you have to get it
at an industrial safety store. IMHO,
Lightspeed is doing it right by starting with the best passive noise
reduction they can get. Bose, for example,
depends almost totally on their active noise reduction, with the result that
their phones are useless if the electronics
fail. If the Solos fail, you still have the best passive phones on the
market.
You should be aware that the single NRR rating is a rather poor way of
rating the protection effectiveness of
ear protectors. It is derived using an average of the results across the
frequency band, emphasizing the HIGH
frequencies (A weighting). The real damage from airplanes comes from the
LOW frequencies, mostly from engine
and prop related sources. Study the noise reduction plots for your headset
and you will find that the protection
ranges from a lowly 15dB or so at 100Hz to above 35dB at 4000Hz. This is
why ANR is so important - it improves the protection to about 30dB in the
low frequencies.
IMHO, even this is not enough for long term use - average noise levels in a
light plane are about 95-105dBA. In the low frequencies, unweighted noise
levels can hit 110-120dB. A better weighting scale for light plane
use is the C scale, which is flatter and designed to reflect continuous low
frequency noise enviroments. In a light plane, C weighted noise levels are
about 6-7dB higher than A weighted levels. Good ANR headsets reduce noise
to about the 80-85dBA range, which is the OSHA 8-hour exposure limit.
However, more recent studies have indicated that the OSHA limit is too high,
and that you should only subject yourself to 85dBA for a maximum of 4 hours
in a 24 hour period. 80dBA is now strongly suggested by several
labs, and 75-78dBA is preferred. IMHO, you need about 40dB noise reduction
at 100Hz to permit continuous
exposure, which is about 10dB more than even the best ANR sets provide.
If you are absolutely serious about the best low frequency noise protection,
use expanding foam earplugs. They
offer 15dB more noise reduction in the low frequencies than the best
headphones, and slightly better noise reduction in the high frequencies.
I, because of hearing damage, use a combination of earplugs and the QFR
solos. The plugs ensure the maximum
low frequency protection and the headphones on top of the plugs
significantly improves perceived high frequency noise. Of course, my
headphone volume is always at maximum.
Take care of your ears.
Shaun
----- Original Message -----
From: <EuropaChris@netscape.net>
Subject: Headset recommendation?
> Hi gang! Yesterday the thermometer hit 49 degrees here in Wisconsin (F,
that is), and it was a *fine* day. Fine enough to get me to the local
airport and sign up for flight lessons. Yes, I know, we are building a
plane and we can't even fly yet. That is what happens when you get a couple
of engineers on a project....:-) Learning to fly is the easy part. It just
takes time and money.
>
> So, I need to buy a good headset that won't break the bank. I've done a
little research and Lightspeed keeps coming up, specifically the QFR series,
either passive or active. From what I've read, they are comfortable,
durable, and the customer service is excellent. Lightspeed was started in
1996 by a group of Tektronix people, and as I have a 1962 Tek 535A
oscilloscope in mint condition that still works perfectly (over 70 vacuum
tubes!), I've got a soft spot for Tek.
>
> The price certainly is right, and you can see them here:
http://www.jaair.com/mailorder/default.asp
>
> Just wondering what others are using and/or recommend?
>
> As a side note, we finally started on the wings over the past month. For
the rib/skin reinforcements, Sue had the idea of laying up a large section
of bid on plastic wrap, say 2' wide cut at 45 deg. and then layup the second
layer on top of that, and then just cut 2" strips, rather than trying to
work with individual 2" strips that never keep shape and fray badly. Other
than trying to work with too large a section of glass at one time, the idea
works incredibly well. Just whack off a full length of 2" wide bid, and cut
to length as you need it. The only suggestion I would make is to only layup
1' wide and then do a second layup. Fortunately, our basement is about 62
degrees, so it gave us enough working time with the glass. After we were
done, I put heat lamps and a small electric heater near the wing to keep the
temp around 70 for 24 hours.
>
> Now to figure how to mount those Aeroflash strobes in the wing tips...
>
> Enjoy!
>
> Chris
> A159
http://webmail.netscape.com/
>
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