Question
On occasion, I will get referrals from employers to perform either baseline audiograms or follow-up audiograms for employees who work in noisy environment. I will commonly perform my standard full audiometric battery, but I am not sure if there are any special procedures that I should be following. Is there a federal standard for this? I need some direction on how I should be testing these types of patients.
Answer
Hearing loss prevention programs (HLPPs), also called hearing conservation programs, will make referral to audiologists who may have limited knowledge of those programs' special needs. Because HLPPs are regulation driven, at least to some variable extent, these programs need to meet regulatory requirements. It is important that referral destinations have some understanding of those requirements.
If in doubt about what is desired from you, ask the referral source. However, here are suggestions about what is always needed:
- Always do a pure tone air conduction audiogram that includes 500, 1000, 2000, 3000, 4000, 6000 and 8000 Hz. Audiograms that come back to the HLPP without 3000 Hz, for example, must be redone so that all frequencies are included. 8000 Hz is an optional frequency per OSHA (Occupational Safety & Health Administration) and MSHA (Mining Safety & Health Administration) regulations but many, if not most, programs like to see it done.
- Insert earphones offer advantages over supra-aural phones of the TDHxx type (Berger & Killion, 1989; Gross, 2005), and may be standard in your office. However, OSHA regulations (1983) reference only supra-aural phones. The OSHA criteria for when insert phones may be substituted for supra-aural phones may be found on the OSHA website www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=21245. Unless collapsing ear canals indicate otherwise, it will be more straightforward for the HLPP to incorporate audiograms done with supra-aural phones. If you do use insert phones, please mark so on the audiogram and give an explanation as to why this was done.
- The audiogram should include identifying information for the person being tested, audiometer serial number and calibration date, and the tester's name and credentials. Audiometric information you provide will probably be computerized, and legibility is very important.
Baseline Audiogram.
If you will be providing an initial baseline audiogram, or the first audiogram for a new employee, you will be providing the gold standard against which subsequent audiograms will be compared. You also have an excellent opportunity to educate the employee about his/her hearing, the audiogram, noise, and hearing protection. Since this initial baseline test is so important you should ensure that the air conduction thresholds are not contaminated by cerumen, middle ear fluid, or other conditions. Even though all that is typically used in a HLPP is the pure tone air conduction audiogram, some employers will allow (will pay for) a comprehensive audiogram with tympanometry. The baseline audiogram should not reflect any temporary threshold shift. The person should be away from hazardous noise for 14 hours. Hearing protection devices can be used as a substitute for this quiet period, but actual quiet (no hazardous exposure) is preferable. Document the person's report of when his/her last noise exposure occurred and if hearing protection devices were used or not.
Monitoring (Annual) Audiogram.
The monitoring test is done to monitor the person's hearing threshold levels for changes, and is typically only an air conduction pure tone audiogram. Because the monitoring test is usually done annually, it is often called an annual test. The monitoring test will be compared to the baseline audiogram for an STS or other change. This comparison is usually done by the HLPP program manager, but if the employer does want you to make a comparison that checks for STS, you will need to know if they use age corrections or not. The OSHA and MSHA regulations (OSHA, 1983; MSHA, 1999) show how age/gender corrections are used when comparing a monitoring test to a baseline audiogram.
Confirmation Audiogram
This person showed an STS on his/her monitoring audiogram and needs at retest to confirm if the STS is persistent or not. If your pure tone air conduction audiogram shows that there is no STS -that the STS is not persistent- then nothing further is needed. However, if the STS persists, many programs may want you to proceed beyond the pure tone air conduction audiogram to check for underlying conditions, such as cerumen or Eustachian tube dysfunction, that may be causing the threshold shift(s). You should check with the employer to see how far into an evaluation you are "allowed" and what they will and won't pay for. If the confirmation audiogram shows that an STS is persistent, then the baseline audiogram, the audiogram against which subsequent annual audiograms will be compared, will need to be revised. A persistent STS may affect both, or only one, ears. Each ear is considered separately when revising a baseline test (Wells, 2005). It is common that an initial baseline audiogram may be used for one ear, and then a revised baseline audiogram, done years later, used for the other ear. If the comparator baseline audiogram were left unchanged in the presence of a persistent STS, the employee would show an STS each year hence on the annual test. Revision of the baseline comparator audiogram is usually done by the HLPP manager.
An employer needs your opinion as to whether an STS is occupationally related or not.
If an STS is occupationally related and the hearing threshold levels for 2000, 3000, and 4000 Hz average 25 dB or more, the employer is required to "record" this incident as an occupational injury (OSHA 2002). In addition to comprehensive audiometry, immittance, history, and other tests you may require for this opinion, you should request all previous audiograms from the employer as well as the noise exposure or noise dose history of the employee. If workplace noise exposure or acoustic trauma caused or contributed to the shift, then the STS is recordable. If you think that the change in hearing is not occupationally related and want to investigate the underlying cause further, you will need to ensure that the patient/employee understand that financial responsibility may rest with them instead of the employer because of the nature of the change.
I have presented some suggestions for audiologists who receive referral from a HLPP and discussed the 4 common reasons for a referral. Occasionally an employer may want an "exit audiogram" for a worker who is leaving employment or whose job no longer involves exposure to hazardous noise. It is always a good idea to talk with the referral source so that you can be sure to provide all the information they require, and so that you can be sure for what procedures you will be paid. I hope you find this information helpful.
References
Berger, E.H. & Killion, M.C. (1989). Comparison of the Noise Attenuation of Three Audiometric Earphones, with Additional Data on Masking near Threshold. J Acoust Soc Am, 86, 1392-1403.
Gross A. (2005). Insert Earphones for Hearing Conservation Testing. Spectrum, 22 (3).
MSHA (1999). "Occupational Noise Exposure Standard." Fed Reg., Vol 65, No 176. U.S. DOL., Mining Safety and Health Administration, Washington, DC.
OSHA (1983). Occupational Noise Exposure; Hearing Conservation Amendment; Final Rule. Fed. Reg. 48:9738-9785. U.S. DOL., Occupational Safety and Health Administration, Washington, DC.
Wells, L. (2005). Audiometric Baseline Revision: Separate or Single? CAOHC Update, 1 (1).
OSHA (2002). Occupational Injury and Illness Recordkeeping and Reporting Requirements; Final Rule, Occupational Safety and Health Administration, Federal Register, Vol. 67, 44037-44048.
Gary Harris, Ph.D. has been an audiologist for 30 years. He is currently president of The HEARING Place (www.hearingplace.com) in South Charleston, West Virginia. His practice involves a mix of hearing diagnostics, hearing aids, and consulting to hearing loss prevention programs.