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 at Etymotic.

The March meeting of the Boston Audio Society will feature Mead Killion Ph.D., Founder, CEO & President of Etymotic Research, Inc.

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 church choir.

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 for attendees.

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 be offered.