We ran an announcement earlier this week about the Voice Alert system, which activates a voice notification whenever a stall or gear horn goes off. The release noted that users of active noise-reducion headsets might find this particularly beneficial, as the noise-cancellation work the ANR sets do is so very good, that a pilot might miss, for instance, a gear horn, at least until the prop starts getting shorter.

ANN readers are everywhere, and it didn't take long for us to get a note from Michael Feldbauer, who happens to be the Product Manager, Aviation/Tourguide, for Sennheiser Electronic Corporation. He volunteered, "As you know, Sennheiser is one the leading manufactures of ANR Aviation headsets. In reading this article (press release) we would like to note a common error: if the ANR is working as designed, it is removing low frequency noise. When you reduce this low frequency noise the noise left is easier to be heard. Since warning devices in aircraft are high frequency, they will be able to be heard better using an ANR headset then using a passive headset. Based on this, it seems that the Voice Alert may help non-ANR users more then ANR users."

Wishing to investigate further, this old Editor wrote to Mr. Feldbauer, asking, "I've been using ANR sets since the first ones came on the market (and I still use my original Telex set), and I've noticed that high frequencies, as well, are attenuated. It's near-blissful, with the set on. Perhaps it's the age of the technology of my set. Have the attenuation curves been significantly altered in the past 10-12 years?"

He replied, "The early Telex unit you speak of also had very good passive attenuation and the passive portion does target mid- and high-frequency noise. Maybe it is time for a laboratory to test and publish the truths about the current technologies and have good data for the pilot population to make decision with." (Our Sennheiser guru may have signed up for some homework...)

FMI: www.sennheiserusa.com/aviation