: I wear DC 10-40, a friend wears Lightspeed 20-something.
: When instrument flying, I can hear the identifier through the background
: noise while my friend cannot. Why? Better headset? Better hearing? Both?

That has also been my experience with the Lightspeed [12][05]'s. My theory is that the 1-2kHz regions where
they're particularly bad at noise reduction is also the most important one for speech intelligibility. The ident on
navaids is 1kHz, too. Basically, I've found that the volume (intercom/radio) for them needs to be so low to not be
painful, that even though they cut out lots of apparent engine noise, it's still very difficult to understand
radios/intercom.

I've also got a friend with an experimental sea-plane with a Rotax 912S in it. I think that cruise RPM is
about 4000-4500, so it really has lots of high frequency. He and I took my Lightspeed XC's up and compared them with
his 25XLs. The 25XLs were basically unintelligible (and painful to me)... the next day he ordered two XC2's (newer
model). To each their own, though.

-Cory

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* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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