A Shift on an Audiogram Is the Start of a Process, Not the Final Answer
An annual audiogram showing a hearing shift does not automatically mean the employee has permanent occupational hearing loss, and it does not automatically make the case OSHA recordable. For employers, the important question is what happens next: compare the result with the correct baseline, determine whether a retest will be used, obtain appropriate professional review when needed, notify the employee, address hearing protection, and separately evaluate OSHA recordkeeping criteria.
For safety and EHS teams managing industrial hearing programs, an OSHA standard threshold shift should trigger a defined follow-up process rather than an isolated test result. Gulf Coast Occupational Medicine provides employer-focused occupational health services, and its current health-surveillance services include baseline and annual audiometric testing.
This article focuses primarily on OSHA’s general-industry noise standard. Employers should verify whether another industry-specific standard, state requirement, or program applies to their workforce.
What Does OSHA Mean by a Standard Threshold Shift?
Under OSHA’s Occupational Noise Exposure standard, 29 CFR 1910.95, a standard threshold shift, or STS, is a change in hearing threshold relative to the employee’s baseline audiogram averaging 10 decibels or more at 2,000, 3,000, and 4,000 Hz in either ear. OSHA permits an allowance for aging when determining whether an STS has occurred using the method in Appendix F.
Under the same general-industry standard, employees exposed at or above an 8-hour time-weighted average of 85 dBA are included in the audiometric testing program, and a new audiogram is required at least annually after the baseline is established. Each annual audiogram is compared with the employee’s baseline to determine whether it is valid and whether an STS has occurred.
For a broader look at program requirements, employers can also review GCOM’s OSHA hearing conservation program guide.
Step 1: Verify the Annual Audiogram Against the Correct Baseline
The first employer step is not to assume the shift is permanent or work-related.
The annual audiogram should be compared with the employee’s appropriate baseline audiogram. If the employee has already experienced a previous recordable hearing-loss case, OSHA’s recordkeeping rule may require comparison with the revised baseline when evaluating a later case.
Employers should maintain an organized hearing-testing history so the person reviewing the results has access to the appropriate baseline, current audiogram, testing information, and relevant noise-exposure records.
Step 2: Decide Whether to Use the Optional 30-Day Retest
If the annual audiogram shows an STS, OSHA allows, but does not require, the employer to obtain a retest within 30 days. The retest result may then be considered the annual audiogram.
A retest can help determine whether the apparent change persists. OSHA has also explained that immediate retesting does not prevent an employer from conducting another appropriate retest within the 30-day period when circumstances warrant it. OSHA’s interpretation on STS retesting
That makes the audiogram retest 30-day provision an important scheduling consideration. Employers should avoid letting the result sit in an inbox until the retest window is nearly over.
Step 3: Route Problem Audiograms for Appropriate Review
OSHA requires an audiologist, otolaryngologist, or physician to review problem audiograms and determine whether further evaluation is needed.
The employer must provide relevant information for that review, including the baseline and most recent audiograms, required hearing-conservation information, audiometric test-room background-noise measurements, and applicable audiometer calibration records.
If an STS determination is made, the employee must be informed in writing within 21 days of the determination.
Turn a Hearing-Test Result Into a Defined Follow-Up Process
If your annual testing program is generating possible threshold shifts, organize the results before the next round of testing. Identify which employees need retesting, which audiograms require professional review, which workers need written notification, and which hearing-protection actions remain outstanding.
Gulf Coast Occupational Medicine lists audiometric testing within its physical exams and health surveillance services and also supports employer hearing testing through clinic and mobile occupational-health capabilities.
Step 4: Address Hearing Protection and Follow-Up
Unless a physician determines that the STS is not work-related or aggravated by occupational noise exposure, OSHA requires follow-up actions.
Employees who are not using hearing protectors must be fitted with them, trained in their use and care, and required to use them. Employees already using protection must be refitted and retrained, with greater attenuation provided when necessary. OSHA also requires appropriate audiological or otological referral when further testing is necessary or certain ear pathology is suspected.
For employees who have experienced an STS, the standard also requires hearing protectors to attenuate exposure to an 8-hour TWA of 85 dBA or below.
An STS should therefore prompt employers to look beyond the audiogram itself. Noise exposure, hearing-protector performance, training, and workplace controls remain part of the larger prevention program. NIOSH recommends focusing first on reducing hazardous workplace noise and maintaining an effective hearing-loss prevention program. NIOSH guidance on preventing occupational noise-induced hearing loss
Employers evaluating workplace noise can also review GCOM’s workplace exposure monitoring guide.
An STS Is Not Automatically an OSHA-Recordable Hearing Loss
This is one of the most important distinctions for employers.
Under OSHA’s occupational hearing-loss recordkeeping rule, 29 CFR 1904.10, an employer records a hearing-loss case when:
- The employee has a work-related STS, and
- The employee’s total hearing level is 25 dB or more above audiometric zero, averaged at 2,000, 3,000, and 4,000 Hz in the same affected ear or ears.
An STS by itself therefore does not automatically satisfy the OSHA 300 Log criteria.
OSHA permits age adjustment when determining whether the STS occurred, but age adjustment cannot be used when deciding whether the employee’s total hearing level reaches the 25-dB recordability criterion.
If an employer performs a retest within 30 days and the retest does not confirm the recordable STS, the case does not have to be recorded. If the retest confirms that the recordkeeping criteria are met, OSHA requires the case to be entered within seven calendar days of the retest.
When Can the Baseline Audiogram Be Revised?
Employers should not automatically replace an employee’s baseline because one annual test shows an STS.
OSHA allows an annual audiogram to replace the baseline when the evaluating audiologist, otolaryngologist, or physician determines that the STS is persistent, or when the annual audiogram demonstrates significant improvement over the existing baseline.
This professional judgment matters because future annual tests may be compared against that revised baseline.
One Annual Audiogram Shows a Possible STS
A Louisiana manufacturing employer completes annual audiograms for employees in its hearing conservation program.
One employee’s annual test shows a possible OSHA standard threshold shift.
Instead of immediately labeling the result permanent or OSHA recordable, the safety manager verifies the baseline comparison and coordinates a retest within the permitted 30-day window. The result is routed for the required professional review.
If the STS is determined, the employee receives written notification, hearing-protection needs are reviewed, and any appropriate referral is coordinated.
Separately, the employer evaluates the case under §1904.10 to determine whether it also meets the work-relatedness and 25-dB hearing-level criteria for OSHA recordkeeping.
That separation helps prevent a common mistake: treating an STS determination and an OSHA 300 Log determination as the same decision.
What to Have Ready Before Scheduling Follow-Up Audiometric Testing
For an OSHA hearing test follow-up, it helps to organize:
- Employee name and job role
- Date of the annual audiogram
- Baseline or revised baseline audiogram
- Most recent audiogram
- Current hearing-protection status
- Relevant workplace noise-exposure information
- Worksite and shift information
- Retest timing, if a retest will be used
- Employer contact responsible for follow-up
- Any unresolved professional-review or referral needs
Having this information available can help the occupational-health provider understand the scope of the hearing-testing request and reduce avoidable administrative back-and-forth.
Build the Follow-Up Process Before the Next Audiogram Finds a Shift
An effective hearing conservation program does not end when the annual audiogram is completed. Employers need a process for identifying possible shifts, scheduling retests when appropriate, routing problem audiograms for professional review, providing written employee notification, addressing hearing protection, documenting follow-up, and separately evaluating OSHA recordability.
Gulf Coast Occupational Medicine provides employer-focused audiometric testing and occupational health support through its Louisiana clinics and mobile services. If your organization is preparing for annual hearing testing or managing employees with possible threshold shifts, have your workforce size, testing dates, locations, and existing audiometric records ready.
Call Gulf Coast Occupational Medicine at (225) 753-7233 or use the GCOM contact page to discuss audiometric testing and hearing-conservation support for your workforce. The main number is currently listed on GCOM’s live contact and locations pages.
Frequently Asked Questions
What is an OSHA standard threshold shift?
Under OSHA’s general-industry noise standard, an STS is an average change of 10 dB or more at 2,000, 3,000, and 4,000 Hz in either ear compared with the employee’s baseline audiogram.
Is a 30-day retest required after an STS?
No. OSHA permits, but does not require, an employer to obtain a retest within 30 days. When obtained within that period, the retest may be considered the annual audiogram.
How quickly must an employee be notified of an STS?
If the comparison indicates an STS has occurred, OSHA requires the employee to be informed in writing within 21 days of the determination.
Does every standard threshold shift go on the OSHA 300 Log?
No. For OSHA recordkeeping, the case must involve a work-related STS and a total hearing level of at least 25 dB above audiometric zero, averaged at 2,000, 3,000, and 4,000 Hz in the same affected ear or ears.
