March 2006 Meeting
Date: Sunday, March 19, 2006
Time: 6:00 PM
Place: Constellation Center, 2nd Floor, 161 1st Street, Cambridge, MA 02141
Featured Guest: Dr. Mead Killion, Founder, CEO &
President of Etymotic Research, Inc.
Topic: General audio topics, and the research directions
The March meeting of the Boston Audio Society will feature
Mead Killion Ph.D., Founder, CEO & President of Etymotic
In the audio world, Etymotic is best known for their
ER-4 and ER-6 earphones, and their High Fidelity and Musician Earplugs.
They also run a full research and development company and have 89 patents.
The name "Etymotic" (pronounced "et-im-OH-tik.") means
"true to the ear." http://www.etymotic.com/aer/
Dr. Killion is an expert in hearing, measuring and protecting hearing, hearing
aids, miniature microphones and receivers ( as used in hearing aids), headphones,
and measuring the response of headphones. He is also an accomplished musician.
He plays jazz piano, classical viola, sings barber-shop, and directs his
Most available evidence suggests that noise exposure
is the predominant cause of hearing impairment in adults. The loss of only
six hair cells in the cochlea a week, for example, will leave none at age
65, yet people voluntarily sit unprotected for two hours in a blues bar
in a steady sound field of 108 dB SPL, unknowingly sacrificing an estimated
120 of their initial 20,000 hair cells. A new $100 pocket dosimeter (patent
pending) provides indications of 25, 50, 100, 200, 400, 1600, and 3200%
of allowable daily dose in a sound field or under earphones, using NIOSH-1998
recommended criteria. The first few 4000 hair cells you lose probably won't
cause many symptoms, but after that it is a slippery slope. Once half the
inner hair cells have been sacrificed, the former owner will probably require
an 8 dB greater signal-to-noise ratio (SNR) than normal to obtain 50% of
words in sentences correctly, an estimate based on Articulation Index data.
This "SNR loss" can be tested in one minute, as will be demonstrated
Lastly, the age-old question of whether people prefer
high-fidelity or colored sound reproduction will be discussed, along with
an outline of Edgar Villchur's and Etymotic's experience with accurate sound
production, with demonstrations of accurate and bass-boom reproduction and
presentations of listener fidelity and preference ratings. Participants
will be asked to participate in listening tests exploring fidelity and preference
ratings. A CD containing two do-it-yourself SNR-loss test blocks and filtered-music
examples representing 25-Band Accuracy Scores ranging from 50% to 100% will