Understanding STS (Standard Threshold Shift) vs. Possible Recordable in Occupational Hearing Loss


Occupational hearing loss is a significant concern for workers exposed to high noise levels. Employers and safety professionals need to understand the difference between a Standard Threshold Shift (STS) and a Possible Recordable to ensure accurate recording and reporting. Let’s delve into these concepts and their implications.

What is an STS?

An STS refers to a change in hearing threshold relative to an employee’s baseline audiogram. Specifically, it involves an average shift of 10 decibels (dB) or more at 2000, 3000, and 4000 hertz (Hz) in one or both ears1. Here are the key points about STS:

  1. Definition: An STS occurs when an employee’s hearing threshold shifts significantly from their baseline audiogram.
  2. Threshold Shift: The shift must be an average of 10 dB or more at specific frequencies (2000, 3000, and 4000 Hz).
  3. Work-Related: The change must be related to occupational noise exposure.

How to Evaluate an STS

A Standard Threshold Shift refers to a situation where an STS has occurred, and the employee’s total hearing level does not meet the 25-dB threshold. To determine whether an STS has occurred, follow these steps:

  1. Compare Audiograms: If the employee has never experienced a recordable hearing loss, compare their current audiogram with the baseline audiogram. If they have previously had a recordable hearing loss, compare the current audiogram with the revised baseline (reflecting their previous recordable case).
  2. STS Present: An STS is evident (average 10 dB or more shift), but the overall hearing level remains within the normal range.
  3. Not OSHA Recordable: Use the average hearing level at 2000, 3000, and 4000 H for the current audiogram to check if the total hearing level is 25 dB or less above audiometric zero.

What is a Possible Recordable?

A Possible Recordable refers to a situation where an STS has occurred, and the employee’s total hearing level meets the 25-dB threshold. Here’s what you need to know:

  1. STS Present: An STS is evident (average 10 dB or more shift).
  2. 25-dB Threshold: Since the 25-dB threshold is met, this case may require recording on the OSHA 300 Log.

Age Adjustment

When assessing an STS, you may adjust the current audiogram to account for age-related changes using Tables F-1 or F-2 in Appendix F of 29 CFR 1910.95. However, age adjustment is not used when determining the 25-dB threshold

Retesting and Confirmation


Understanding the distinction between STS and Possible Recordable is crucial for maintaining accurate records and ensuring worker safety. By following these guidelines, employers can effectively manage occupational hearing loss and protect their employees’ well-being.

Remember, every decibel matters when it comes to hearing health!

Workplace Integra is committed to promoting safety and well-being in the workplace. Our website, WorkplaceIntegra.com, offers a wealth of resources, expert insights, and practical solutions for occupational health and safety. Whether you’re an employer, safety professional, or employee, you’ll find valuable information to enhance workplace safety practices. Explore our site today and empower your organization with knowledge that matters!