John Young of Puget Sound Hearing and Balance speaks to the PNW Section at June 2009 meeting at Shoreline CC.
The PNW Section held its June 2009 general and business/elections meeting at Shoreline Community College in Shoreline, WA, north of Seattle. The featured speaker was John Young of Puget Sound Hearing and Balance, discussing hearing, hearing conservation, and hearing assistance devices featuring a local case study, retired CBS Records engineer Frank Laico. Many attendees were from Shoreline's audio technology program. 16 AES members and 9 non attended (25 total)
John started by distinguishing between research audiologists and clinical audiologists such as himself. Then he showed how hearing is measured with the audiogram, the chart showing the person's hearing response deviation from normal. Such a chart may seem obvious to an audio person, but many ordinary patients never have this explained to them, or told what it means for their treatment. Any loss is described variously as "mild, moderate, severe, profound" The typical testing stops at 8k-12kHz.
John continued with how we hear, describing the parts of the ear (the outer, middle and inner ear) and how they function. He described the stapedial or acoustic reflex, which is a human built-in protection from loud sounds. It only works for about 15 seconds, even though it gives a nice 30dB attenuation. It diminishes with hearing loss.
There was a simplified discussion of speech processing in the brain - highs for consonants and clarity; lows for vowels and loudness. Thus a hearing aid needs to be tailored for a person. Just because the sound is loud doesn't mean the person will understand it.
Next was a discussion of noise, noise exposure, and the measurement of sound and noise. Regarding noise exposure and the law, the American NIOSH standard is 85dBA for 8 hours. OSHA is 90dBA/8 hours. These are probably not adequate. NIOSH also says for an increase of 3dB, halve the exposure time. Over 115dBA, don't be in it unprotected. OSHA & NIOSH standards were compared, and a chart of dBSPL of various common sounds was shown.
Noise causes loss by acoustic trauma (damage). This physically damages the hearing bones and hair cells. The consequences of loss include tinnitis (ringing in the ear, and as the loss gets worse, the ringing get louder), sleep disturbance, poor concentration, mood swings, stress, decreased sound tolerance, and depression/isolation.
John played an audio example that simulated before and after various hearing losses. Problems from hearing loss were discussed such as loudness recruitment (abnormal sensation of dynamics), pitch distortion, problems localizing, vestibular (balance) problems and temporary threshold shifts.
Personal music player loss was mentioned, as people listen longer and louder. Surprisingly to some, it seems 30% of rock & 58% of classical musicians have hearing loss. Also cited were hearing losses by music teachers, bar and club wait staff, sound engineers, and DJs.
A break was held for the Section elections.
Continuing after the break, John discussed several ways to conserve our hearing. He also suggested getting regular hearing exams - often health insurance covers them. In discussing the hearing test, John said that fakers are obvious. They sometimes try to falsify a hearing test to win a hearing loss lawsuit. Hearing protection devices were discussed next.
Finally, a local case study with retired CBS Records engineer Frank Laico was presented. He already had hearing aids, but was dissatisfied, and came to John's clinic. He had hearing loss, tinnitis, imbalance, and a perforated right eardrum (from a botched cleaning treatment). Eardrum repair attempts (tympaniplasties) were not good, and he needed a "cholestiatoma" (growth behind the eardrum) removed. Tests showed this condition.
Frank's chart with profound loss was shown. After a careful analysis of his condition, new hearing aids were prescribed which he found to be much better. One interesting feature of the new aids was the capability to transpose frequency channels into a hearer's more sensitive channels. PNW Committee person Bob Smith created a simulation of what Frank might hear. While it may sound distorted to a person with normal hearing, the tranposition of some sounds allows a patient to finally hear important speech sounds at last, and the brain can easily adapt to the "new" sound and learn to understand it.
Unabridged report at the PNW website, http://www.aes.org/sections/pnw/pnwrecaps/
