COHC case studies
COHC · Put your knowledge to work in context.
The Certified Occupational Hearing Conservationist (COHC) credential is administered by the Council for Accreditation in Occupational Hearing Conservation (CAOHC), a council whose training catalog includes seven different certifications and certificates plus webinars, with the COHC as its best-known offering. The credential is aimed at the people who actually run an employer's hearing conservation program day to day - occupational health nurses, technicians, safety staff, and others who take audiograms, fit hearing protection, deliver worker education, and maintain the records a hearing conservation program depends on. The COHC case studies are 5 cases and about 3,255 words.
1A First-Time Program at Ridgeway Metalworks
Ridgeway Metalworks stamps and welds sheet steel on two shifts. An 8-hour dosimetry survey of the 40-person production floor found 11 employees at 87–89 dBA TWA, 9 at 92–95 dBA TWA (including a welder with nine years' service), and the remaining 20 below 82 dBA.
676 words, about 3 min2Dosimetry That Disagrees With the Sound Level Meter
A 60-person injection molding plant sampled noise with a Type 2 logging dosimeter worn by six machine operators. The instrument was configured with A-weighting, slow response, a 3 dB exchange rate, and an 80 dB threshold; it reported 8-hour TWAs of 89–93 dBA.
637 words, about 3 min3A Notch, Tinnitus, and a Question About Recovery
A 41-year-old press operator with 14 years in a 95 dBA stamping department reports constant high-pitched ringing and difficulty understanding conversation when two machines run at once, although he says his hearing is "fine one-on-one." His audiogram shows right ear thresholds of 10 dB at 500 and 1000 Hz, 20 dB at 2000 Hz, 45 dB at 3000 Hz, 55 dB at 4000 Hz, 40 dB at 6000 Hz, and 25 dB at 8000 Hz; the left ear is about 10 dB better at each frequency. Otoscopy is clear and tympanometry is normal.
649 words, about 3 min4Computing an STS on a Possibly Invalid Annual Audiogram
At a concrete products plant, an employee's baseline audiogram was recorded at age 44 and the annual audiogram at age 45. Baseline right ear: 10 dB at 500 Hz, 10 at 1000, 15 at 2000, 20 at 3000, 30 at 4000, 25 at 8000.
659 words, about 3 min5The NRR 32 Plug That Wasn't Working
A saw operator in a pallet mill has an 8-hour TWA of 98 dBA from a 10-hour shift. His annual audiogram shows a confirmed standard threshold shift in the left ear.
634 words, about 3 min