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ANNUAL AUDIOGRAM BASED UPON

OSHA GUIDELINES  

 

 
 

  After obtaining the baseline audiogram, employers must obtain a new audiogram annually for each employee whose exposure is at or above the action level.

STANDARD THRESHOLD SHIFT

A standard threshold shift (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. [1910.95(g)(10)(i)]

In determining whether an STS has occurred, allowances may be made for the contribution of aging (presbycusis) to the change in hearing level by correcting the annual audiogram according to the procedure described in 1910.95 Appendix F: Calculations and Application of Age Corrections to Audiograms. [1910.95(g)(10)(ii)].  Most industrial audiology software program automatically computes age corrections.

Computing the Standard Threshold Shift

Example 1

Frequency (Hz)

Baseline audiogram threshold (db)

Annual audiogram threshold (dB)

Change

500

5

5

0

1,000

5

5

0

2,000

0

10

+10

3,000

5

20

+15

4,000

10

35

+25

6,000

10

15

+5


Considering the Hearing Threshold Level (HTL) values at 2,000, 3,000, and 4,000 Hz, there are changes in hearing threshold of 20, 15, and 25 dB, respectively. Thus:

STS = (10 + 15 + 25)/3 = 50/3 = 16.7 dB
 


Conclusion: The STS is +16.7 dB; hearing has deteriorated, the employee must be notified in writing within 21 days, and, depending on professional discretion, the employer may elect to retest the employee and/or revise the baseline audiogram.

Example 2

Frequency (Hz)

Baseline audiogram threshold (db)

Annual audiogram threshold (dB)

Change

500

5

5

0

1,000

5

0

-5

2,000

0

-10

-10

3,000

5

-5

-10

4,000

10

-5

-15

6,000

10

5

-5


Again, considering the HTL values at 2,000, 3,000, and 4,000 Hz, the hearing threshold has changed by -10, -10, and -15 dB, respectively. Thus:

STS = (-10 -10 -15)/3 = -35/3 = -11.6 dB
 


Conclusion: The STS is -11.6 dB; hearing has improved, the employee should be notified, and, depending on professional discretion, the baseline audiogram may be revised.