Noise

• OSHA uses a 5 dB doubling rate (aka, exchange rate).  For every 5dB increase, maximum time until 100% dosage halves.
• Peak: At no point during an employee's work shift should they be exposed to a sound pressure level over 140dB C-weighted.
  • NOTE: I previously had non-weighted (otherwise known as Z-weighting) because no OSHA reference material or publications seen by me had reference to weighting as it applies to peaks. However, the ACGIH and others set this limit with C-weighting.
• Error Factor → The error of the dosimeter must be factored in to the consideration of a violative condition.
  • For example, the dosimeters used at KYOSH are Type II dosimeters. This indicates an error of 2 dB.
  • A Type I dosimeter has an error of only 1 dB.

Noise Standards

For Noise Exposure — 1910.95(a) and (b)

• Exchange (Doubling) Rate: 5 dB
• Criterion Level: 90 dBA
• Threshold: 90 dBA*

For Hearing Conservation — 1910.95(c) (General Industry amendment; not Construction)

• Exchange (Doubling) Rate: 5 dB
• Criterion Level: 90 dBA
• Threshold: 80 dBA*

*See OSHA Tech Manual Section III, Chapter 5, I.A.3. and I.A.4.

Standard Threshold Shift (STS)

An STS is a change in hearing threshold relative to the baseline audiogram of an average of 10 dB or more at 2000, 3000, and 4000 Hz in either ear.

• When a STS has occurred and the employee’s hearing level is at least 25 dB above audiometric zero in the same ear, the hearing loss is recordable on 300 logs.

• If a STS has occurred, you set this new audiogram as the Revised Baseline Audiogram.

Substance Codes

8111

Hearing Conservation Program (Action Level @ 50% dose / 85 dBA)

8110

Engineering Controls (PEL @ 100% dose / 90 dBA)