From the Desk of Gus Mueller
Our topic this month is Industrial Audiology. When did this sub-specialty of our profession originate? The facts are a little murky, but we do know that the US Occupational Safety and Health Administration (OSHA) Noise Exposure Regulation became effective in 1971. We’ll stick with that time frame for the moment, as it ties in nicely with the little story I’d like to tell. The story relates to the U.S Army, which indeed is not an industry, but from a hearing conservation standpoint, there are many similarities.
Unlike today, obtaining a degree in audiology was fairly popular for males in the late 1960s, but many also had a military obligation—people like Harvey Abrams and Gus Mueller come to mind. Serving as a military audiologist, however, was blocked because of the low quota allowed for that specially—something like only 10 for the entire U.S. Army—and hence, these newly minted audiologists were commissioned into other branches, like the infantry (with a Viet Nam assignment on the horizon).
All this changed, however, in 1969 when Captain Jerry Northern, one of the first Army audiologists, and Chief of Audiology at Walter Reed Hospital, was interviewed by the Associated Press, questioning how the military protected soldiers’ hearing. Northern (who neglected to have his interview approved by the Public Affairs Officer) was quoted by the reporter as saying, “…hundreds of thousands of soldiers each year suffer permanent hearing loss in training. They are then sent to Viet Nam unable to hear the enemy properly.” The Associated Press released the story to their 1200 papers across the U.S. with a photograph of a soldier stuffing cigarette butts into his ear canals to protect his hearing. Captain Northern was further quoted as saying, “Although hearing conservation is mandated by military regulation, it is poorly, if ever, implemented.”
The widespread publication of the lack of hearing conservation in the military, as described by Jerry, quickly drew the attention of the U.S. Congress. The House Public Health Committee asked the Secretary of the Army to explain why the Army had not followed its own recommendations to prevent “partial deafness” in military trainees. The Army responded by quickly allocating 16 more slots for military audiologists—Mueller was soon informed he would receive a branch transfer from the infantry to the Medical Service Corps!
As lot has changed in the world of hearing conservation over the past 50 years, although a few things have stayed pretty much the same. To tell us all about it is this month’s 20Q guest author Deanna Meinke, PhD, Winchester Distinguished Professor in the Audiology and Speech-Language Sciences program at the University of Northern Colorado. You all know her from her many publications surrounding the early detection and prevention of noise-induced hearing loss, educational gaming to promote hearing health, and the use of wireless automated hearing test systems. To honor her many years of excellent research, she recently received the “Jerger Career Award for Research in Audiology” from the American Academy of Audiology.
Dr. Meinke’s other numerous awards include being named the “Outstanding Hearing Conservationist” from the National Hearing Conservation Association, where she also has served as president. She presently is the Co-Director of the Dangerous Decibels® program. Back in the early 1990s, Deanna was a founder and served as president of the Colorado Academy of Audiology.
Speaking of Colorado, earlier we were talking about Jerry Northern, one of Colorado’s most famous audiologists (not named Marion Downs). Deanna, however, also has a pretty amazing Colorado history. Other than a short stay in Illinois to obtain her Master’s Degree, since birth she has never lived anywhere else but Colorado! As you read her excellent 20Q article, you’ll find that her commitment to industrial audiology is almost as strong as her dedication to the Centennial State.
Gus Mueller, PhD
Browse the complete collection of 20Q with Gus Mueller CEU articles at www.audiologyonline.com/20Q
20Q: Occupational Audiometry
After reading this article, professionals will be able to:
- Identify five differences between the Occupational Safety and Health Administration (OSHA), the Mine Safety and Health Administration (MSHA) and the Federal Railroad Administration (FRA) in the context of audiometric monitoring requirements and determination of hearing threshold shifts.
- List best practices for occupational hearing testing.
- Calculate a standard threshold shifts (STS) and classify a hearing loss as OSHA “recordable” or MSHA “reportable”.
1. Glad we are having this conversation. I’d really like to boost my knowledge in the area of occupational hearing conservation.
Hopefully, I can help. It certainly is an important area of the profession of audiology, and there is a large population to be served. Kerns et al. (2018) report that 25% of current U.S. workers report a history of occupational noise exposure on the 2014 U.S. National Health Interview Survey. These workers require audiometric testing as part of hearing conservation programs in an effort to prevent noise-induced hearing loss (NIHL).
2. Where do I start?
Well, as tedious as it might sound, one of the first things to do is become familiar with the many laws and regulations surrounding the programs and the different guidelines related to conducting audiometric testing. I’ve put together a list of some of the most common noise/hearing conservation regulations and resources to get you started.
Summary of U.S. regulatory requirements for conducting hearing tests for workers exposed to hazardous noise:
- Workers in general industry (manufacturing and service industries) fall under the Occupational Safety & Health Administration (OSHA): “Occupational Noise Exposure,” Occup. Safety and Health Admin., 29CFR 1910.95 Fed. Regist. 48, 9738-9744 1983 rule. OSHA uses the term “general industry” to refer to all industries not included in agriculture, construction, or maritime. OSHA applies to employers with more than 10 workers. Other resources include:
- Mine workers are covered by the Mine Safety and Health Administration (MSHA): “Health Standards for Occupational Noise Exposure; Final Rule,” Mine Safety and Health Admin., 30CFR Part 62, 64, Fed. Regist. 49458-49634, 49636-49637, 1999. Effective September 13, 2000.
- MSHA (2000). “Compliance Guide to MSHA’s Occupational Noise Exposure Standard,” U.S. Department of Labor Mine Safety and Health Administration.
- Railroad workers are covered by the Federal Railroad Administration (FRA): “Occupational Noise Exposure,” 49CFR 1.89, Oct. 27, 2006, as amended at 73FR79702 part 227, Dec. 30, 2008, Fed. Regist. 71, 63123.
- Federal Railroad Administration Compliance Manual for Occupational Noise Exposure for Railroad Operating Employees 49 CFR Part 227 AND Locomotive Cab Noise Standard 49 CFR Part 229.121.
- Requirements for military personnel are specified by the U.S. Department of Defense (DoD):
- The construction industry is regulated under 29 CFR 1926.52.
3. Some of these regulations are almost 40 years old. Are there better ways to do things now?
Some of them are older, yes, but the National Institute for Occupational Safety and Health (NIOSH) provides updated evidence-based best-practice guidance for the prevention of NIHL in the workplace. For example, we have Criteria for a Recommended Standard: Occupational Noise Exposure Revised Criteria (1998). However, we are looking forward to another update from NIOSH in the near future.
In the meantime, the NIOSH website is a good place to find current research, publications, and educational resources.
4. In different documents, I have seen both the terms “industrial screening” and an “industrial hearing test”? Same or different?
Importantly, they are different—there is a clear distinction between the two terms. Regulatory agencies such as OSHA, MSHA, and FRA specifically refer to “audiometric testing” and not “screening”. A hearing screening is a simple and quick means of identifying individuals who might have a hearing loss that impacts speech communication and needs a referral for follow-up testing. Adult hearing screening guidelines specify that screening is performed with the audiometer set at a supra-threshold level (typically 25 dB HL) for a subset of test frequencies (e.g., 1000, 2000, and 4000 Hz) (ASHA, n.d.). Screening outcomes are reported in terms of a “pass” or “refer” status for the listener.
Occupational hearing tests, on the other hand, are conducted using pure-tone air-conduction audiometry methods, and the outcome measure is a hearing threshold which represents the softest sound a listener can detect 50% of the time (ANSI/ASA S3.21-2004 (R2019)). Occupational hearing testing provides a record of hearing thresholds documenting how a worker hears at a given place and time. Screening does not provide threshold values that can be compared over time in order to identify subtle changes in hearing indicative of early NIHL. We should avoid using the term “industrial screening” when testing hearing for regulatory purposes.
5. What frequencies have to be tested? Is it the same for all workers?
There is some variation among the different regulations regarding the testing of 8000 Hz. All require audiometric testing at 500, 1000, 2000, 3000, 4000, and 6000 Hz, but OSHA and MSHA do not require 8000 Hz. Testing at 8000 Hz, however, is required for FRA. The U.S. DoD advises testing 8000 Hz “if applicable” and does not provide further clarification. Guidelines from the American College of Occupational and Environmental Medicine (ACOEM) recommend that 8000 Hz be tested since this information assists in the identification of a noise “notch” as well as age-related hearing loss (Miza et al., 2018). NIOSH (1998) recommends testing 8000 Hz as a best practice. These specifications would then apply to all the different occupational hearing tests.
6. Different hearing tests? Not sure what you mean.
There actually are five different classifications of audiometric testing, for the most part, related to the reason the test is being conducted.
- Pre-employment (Pre-placement) Audiogram: A hearing test conducted prior to employment of an individual. These audiograms are often obtained as part of a comprehensive pre-employment physical exam. These test results may also be used to determine if the job candidate is eligible for the position when hearing ability is a prerequisite for job performance (e.g., Federal Aviation Administration (FAA); Department of Transportation (DOT)).
- Initial Baseline Audiogram: The first hearing test conducted when a worker is first enrolled in a hearing conservation program and used to evaluate future changes in a worker’s hearing sensitivity when compared with subsequent periodic audiograms. The timelines for obtaining the baseline audiogram are within 6 months of an employee’s first noise exposure at or above 85 dBA time-weighted average (TWA) or within 1 year if mobile testing services are used. Typically, mobile testing services contract with employers and bring a trailer or truck equipped with automated hearing test equipment, operated by audiometric technicians, to efficiently test a large number of workers at the worksite. This 1-year mobile-testing exception applies to employees tested according to OSHA, MSHA, and the FRA. Best practice would be to use the preplacement exam (if no pretest noise exposure is documented) or obtain the baseline test within 30 days of enrollment in the hearing conservation program (noise exposure at or above 85 dBA TWA).
- Periodic Monitoring Audiogram: A repeat hearing test conducted within a specified interval of time, typically annually (within 12 months) for OSHA and MSHA. However, the FRA requires that audiometry must be offered annually to all workers once each calendar year if exposure is ≥85 dBA TWA. Mine workers can take a hearing test at their discretion per the regulation, however, most mines require audiometry as a “condition of employment”. The interval between the date offered for a periodic test in a calendar year and the date offered in the subsequent calendar year shall be no more than 450 days and no less than 280 days. Testing is required at least once every 1095 days (3 years) for railroad workers. NIOSH (1998) best practice recommends annual testing for workers exposed to >85 dBA to 100 dBA time-weighted average (TWA) noise and bi-annual testing (every 6 months) for workers exposed to >100 dBA TWA.
- Retest for significant standard threshold shift or significant change in hearing from baseline test: A repeat hearing test that can be conducted within 30 days for workers whose periodic audiogram meets the criterion for a “standard threshold shift (STS), which is a change in hearing ≥ 10-dB average shift from baseline test hearing levels at 2000, 3000, and 4000 Hz in either ear is stipulated by OSHA and MSHA. The FRA allows up to 90 days for the retest. The retest can then be substituted for the annual periodic audiogram. Both ears must be re-tested, not just the ear exhibiting the STS. Age adjustments may be applied under each of these regulations. The NIOSH (1998) shift criterion is a threshold change for the worse ≥ 15 dB from baseline at any test frequency (500–6000 Hz), in either ear. An immediate retest is recommended to determine if the STS is persistent. If persistent, a retest within 30 days is suggested to confirm the persistence of an STS.
- Exit or Transfer Audiogram: NIOSH recommends a hearing test be obtained when an employee leaves employment or when a worker is transferred and noise exposure is no longer ≥ 85 dBA TWA. OSHA, MSHA or FRA do not mandate this type of test, although it would be useful information when considering a workers’ compensation claim.
7. Do you ever retest someone during the same session?
Sometimes, yes, and research has shown that this can be a useful procedure to follow. NIOSH (1998) recommended an immediate retest based on the work of Royster (1992; 1996). This permits the audiometric technician or audiologist to correct any subtle differences in test procedures that might contribute to the STS. An immediate retest is conducted by removing the earphones, reinstructing the worker to make sure the test-taking instructions are well understood, then replacing the earphones paying close attention to proper placement (including right/left placement) and retesting in an environment that meets the minimum permissible ambient noise levels for audiometric testing. If the immediate retest is improved and eliminates the presence of an STS, the retest is substituted for the annual exam. Rink (1989) estimated that more than 70% of the 30-day retests can be eliminated if an immediate retest is conducted. It makes sense from a practical point of view if you think about it. Workers are arriving for a hearing test after working hard, they may be tired, they may speak a language other than English, and the tests are done quickly to be time efficient at the worksite. Simply repeating the test can save time, expense, and effort for all when a worker exhibits an STS.
8. Can it be challenging to keep workers from being noise-exposed before their hearing tests?
The baseline hearing test and the 30- or 90-day retest should be performed after the worker has had a 14-hour “quiet period”. All the regulatory agencies allow the use of hearing protection as an alternative to a quiet environment. Although this is permitted, it is less than an ideal substitution for “quiet”, as we know that not all workers are fitted properly with adequate attenuation to assure no temporary threshold shifts have occurred. Murphy et al. (2016) found that less than half of the workers were achieving sufficient protection from their hearing protectors when attenuation was measured in the field. A 14-hour quiet period is not required for the annual/period exam. This way, the annual/periodic test can provide early detection of noise induced hearing loss and allows for early intervention to prevent NIHL.
9. Do you ever revise the baseline audiogram?
The Occupational Safety and Health Administration (OSHA), and the Mine Safety and Health (MSHA) permit the baseline to be revised by the reviewing audiologist or physician either for significant improvement in measured thresholds or for persistent/permanent standard threshold shift (STS). The Federal Railroad Administration (FRA) states that the baseline revision should be done by a professional supervisor (audiologist or physician) in accordance with the National Hearing Conservation Association (NHCA) “Guidelines for Baseline Revision” and were incorporated into Appendix C of the regulation. These can be found here. Baseline revision is done for each ear independently and will need to be accurately documented within the audiometric database.
10. What’s the point of identifying an STS if the baseline is just revised?
The rationale for testing a worker’s hearing regularly is to detect noise-induced hearing loss in the early stages and intervene before a change progresses and becomes a permanent hearing loss.
When an OSHA STS is detected and persists on retesting, the following actions are required; 1) notify the worker regarding the change in hearing within 21 days and 2) fit or refit hearing protection to assure adequate attenuation, 3) trained in use and care of earplugs/earmuffs and are required to use them. MSHA requires the same follow-up as OSHA but allows 30 days for notification to the miner and adds a requirement to review the effectiveness of any engineering or administrative noise controls to correct deficiencies. FRA also allows 30 days to notify the railroad worker. The audiogram will need further review to determine if the STS may need to be recorded as a work-related injury on the OSHA 300 log. Referring the employee for a clinical evaluation and/or otological examination may also be required and will assist in the determination of a work-related hearing injury. NIOSH (1998) expands on these recommendations and states that the employer must take action beyond the 30-day STS notification and recommends that the effects of noise be explained to the worker and that the worker be retrained on hearing loss prevention strategies. The employer can also consider reassigning the worker to a quieter work area. So, the purpose of the baseline revision is not to neglect the change in hearing but rather to reset the monitoring reference test to avoid repeat identification of the same change in hearing.
11. I understand that there are “age corrections?” I really do not know how to use them.
The use of age corrections is optional and is allowed when calculating an STS for OSHA, MSHA, and FRA. NIOSH (1998) does not advise the use of age corrections. In order to use age corrections, you need to have the worker’s birthdate and sex recorded on the audiogram. OSHA provides a step-by-step guide for calculating age-corrections.
Examples are also provided in the OSHA Technical Manual (OTM) Section III: Chapter 5: Noise, Appendix. The approach is the same for MSHA and FRA. While age-corrections are permitted, it is important to ensure that the referenced age-corrections are valid and correct for the individual worker (Flamme et al., 2019).
12. I have heard that the OSHA age correction tables are outdated. True?
Not anymore. OSHA issued a Technical Directive (TED-01-00-015) on April 28, 2022 that updates OSHA Technical Manual – Section III, Chapter 5, Noise. The directive allows the use of new population-based age adjustment tables (age range: 18-85) that were developed using U.S. National Health and Nutrition Examination Survey (NHANES) audiometric data by Flamme et al. (2020). The updated age adjustments were validated using a database of noise exposed workers (male firefighters and emergency medical service workers). Differences in cross-sectional trends implied less change with age than assumed in current U.S. hearing conservation regulations and different trends were observed among people identifying with non-Hispanic Black race/ethnicity. OSHA has approved the use of the four new age adjustment (correction) tables; 1) Men Non-Hispanic Black race/ethnicity, 2) Men Other race/ethnicity, 3) Women Non-Hispanic Black race/ethnicity and 4) Women Other race/ethnicity. The full age adjustment tables are available as supplemental materials to the original publication.
Implementation of the new age adjustments will necessitate audiograms to not only include the birthdates of workers but also information regarding their self-reported race/ethnicity.
13. Are there other early indicators of NIHL besides the OSHA “standard threshold shift?”
The audiometric monitoring program is in place to facilitate the early identification of noise-induced hearing loss, but there are other early indicators of NIHL. NIOSH uses the criterion of a threshold change for the worse ear ≥ 15 dB from baseline at any test frequency (500–6000 Hz). This permits the earliest detection of a change in hearing based again on work by Royster (1992; 1996). Although we recognize that NIHL occurs primarily in the high frequencies first, occupational hearing loss from chemical exposures may also be ototoxic and results in hearing losses at other test frequencies and may need alternative methods of detection such as otoacoustic emissions (Campo et al., 2013). Rabinowitz et al. (2007) recognized that the OSHA STS does not serve as the earliest indicator of NIHL and conducted a longitudinal analysis of industrial audiograms to evaluate the calculated time from an audiometric “red flag” event to the 10-year risk of recordable hearing loss. The 10 dB non-age-corrected STS and the 8 dB age-corrected shift averaged at 2000, 3000, 4000 Hz provided the best predictive value in terms of length of time to a recordable hearing loss. With audiometric data residing in computerized databases, it may be useful to utilize alternative early indicators of NIHL in order to intervene more proactively with prevention efforts.
14. A couple of times, you have mentioned “recordable” or “reportable” hearing losses. What exactly does that mean?
OSHA 29 CFR Part 1904 requires employers with more than ten employees to keep a record of serious work-related injuries and illnesses using the OSHA 300 Form. Criteria for recording cases of occupational hearing loss have changed over the years and were most recently revised in 2002 and can be found here. Currently, an OSHA “recordable” work-related hearing loss must meet a two-stage criterion: 1) the employee’s hearing tests reveal that the employee has experienced a work-related STS in one or both ears and 2) the employee’s total hearing level is 25 dB or more above audiometric zero (averaged at 2000, 3000 and 4000 Hz) in the same ear(s) as the STS. In audiology terms, it means that the worker had an STS and in the same ear on the same test, the pure-tone average (PTA) for 2000, 3000, and 4000 Hz is ≥25 dB HL. The Federal Railroad Administration requires occupational hearing loss to be reported on the FORM FRA F 6180.55a and the criteria is the same as OSHA.
The determination of work-relatedness is determined by a physician or audiologist, and in best practice, the determination would be a collaborative effort between the two professions. The Council for Accreditation in Occupational Hearing Conservation (CAOHC) provides training and certification for “Professional Supervisors,” which provides training on supervising the audiometric portion of a hearing conservation program and determining work-relatedness. Additional information can be found here.
The term “reportable” is used by MSHA and the criteria for reporting on the MSHA Form 7000 is different from OSHA. In this case, the change from the baseline audiogram shifts by 25 dB or more when calculating the average change at 2000, 3000 and 4000 Hz in either ear. So, essentially, the progression of NIHL has created a 25 dB average shift from the original reference baseline. Hence, separate ear baselines are tracked independently for both a 10 dB STS and a reportable STS when reviewing miner audiograms. This is a substantial amount of hearing change if the reviewer applies age-corrections.
15. I have conducted some testing after a worker was referred due to having an OSHA STS. My results often are better than the annual test performed by the company. Is this common?
This is not a surprising observation when one considers that OSHA permits testing to occur in higher levels of background noise than ANSI/ASA S3.1-1999 (R2018). Therefore, if the worker’s thresholds are slightly elevated by background noise during occupational testing, then a subsequent test conducted in a clinical sound booth environment that meets the maximum permissible ambient noise levels (MPANLS), will result in lower hearing thresholds. Dobie (1983) found that clinical audiograms were 3 to 7 dB better than the industrial tests. He also found larger test-retest reliability (6-10 dB) which he attributed to testing in “real-world” industrial conditions. Another reason might be that the clinical tests are often scheduled in the morning after the worker has been away from noise for 14 hours. If the worker was exposed to high levels of noise before the annual audiogram, it may show up as a temporary threshold shift. This situation should trigger a follow-up to assure that hearing protection is fit-tested to assure adequate attenuation and that the earplugs and/or earmuffs are worn consistently both on and off the job.
16. What about the use of automated computerized testing?
Automated audiometry works well and serves to standardize the testing even further. It has been widely embraced for occupational hearing testing. Recently, Mahomed et al. (2013) used a meta-analytical approach and concluded that that air-conduction hearing thresholds obtained using automated audiometry were within typical test-retest reliability for manual audiometry (Mahomed et al., 2013).
17. Are hearing thresholds obtained in hearing conservation programs used for other purposes?
Yes, these hearing tests provide a historical record that inform workers’ compensation cases. Occupational hearing tests are also used to request accommodations under the Americans with Disabilities Act (1990). Baseline test results may be used to evaluate whether a worker has hearing levels sufficient to meet hearing sensitivity employment criteria or fitness for duty. For instance, the Federal Highway Administration (FHWA, 1994) specifies hearing criteria for commercial truck drivers based on air-conduction hearing thresholds which need to be 40 dB HL (or lower) averaged across 500, 1000, and 2000 Hz, when tested with or without a hearing aid in one (better) ear only. There are other employment criteria for emergency personnel, police, wildlife officers, commercial pilots, and other jobs that require adequate hearing to safely perform a job which are beyond the scope of our discussion.
18. Are there any special considerations for workers with hearing impairment?
Workers with hearing impairment are still expected to be included in hearing conservation programs. However, they may have unique needs that need to be addressed to assure adequate communication, selection of suitable hearing protection devices, and determine the conditions that allow the use of hearing aids at work. OSHA provides guidance for employers in a 2005 Safety and Health Information Bulletin, available here. Essentially these issues must be addressed on a case-by-case basis by the supervising hearing conservation professional (audiologist or physician) to ensure that the worker does not incur additional hearing loss from hazardous noise exposure. The audiologist can also provide recommendations for assistive technology that will facilitate communication while in hearing conservation group trainings or workplace meetings, and ensure the worker is alerted to emergency notifications.
19. Can occupational testing be conducted without a sound booth?
There is lots of interest in “boothless” audiometry, and occupational audiometry can certainly be conducted outside of a sound booth providing the proper MPANLS are referenced for the transducer being used for testing and that ambient noise levels are monitored. Since the attenuation of background noise is different for each transducer, MPANLS differ as well. This means that you wouldn’t just blindly apply the MPANLS for supra-aural earphones to any type of earphone. The OSHA MPANLS are based upon the use of supra-aural earphones only and do not permit testing to 0 dBHL at all test frequencies. Appendix A of the ANSI/ASA S3.1-1999 (R2018) standard specifies how to determine the MPANLS for any transducer. Since this information is not readily available to hearing conservationists and audiologists, Elliott Berger has created a spreadsheet calculator that will allow one to determine the MPANLS for testing to 0 dB HL for a specific transducer. The “Audiometric Testing, Ambient Noise Calculator” is available from the National Hearing Conservation Association. To use the calculator, you will need the mean attenuation of the transducer, and this should be measured according to ANSI/ASA S12.6-2016 (ANSI, 2020). Meinke and Martin (2022) advise using the standard deviation for the measured attenuation when calculating MPANLs in order to prevent masking in a larger proportion (84%) of the population. Additional ambient noise considerations when conducting audiometry outside of a sound booth are addressed in the article by Meinke and Martin (2023).
20. Where can I learn more about hearing conservation programs and prevention of NIHL?
Without sounding self-serving, I had the pleasure of co-editing the 6th edition of “The Noise Manual”.
The book contains 21 chapters written by experts representing diverse fields including industrial hygiene, occupational medicine and nursing, audiology, physics, hearing science, engineering, and public health, to name a few. It will provide state of the art updates on every aspect of NIHL and prevention of the disorder. For the record, none of the editors or authors receive any royalties.
Other resources include the Council on Accreditation in Occupational Hearing Conservation and the National Hearing Conservation Association.
American Speech-Language-Hearing Association (ASHA) (n.d). Adult Hearing Screening (Practice Portal). https://www.asha.org/practice-portal/professional-issues/adult-hearing-screening/.
Americans With Disabilities Act of 1990, 42 U.S.C. § 12101 et seq. (1990). https://www.ada.gov/pubs/adastatute08.htm
American National Standards Institute. (2018). S3.1, Maximum permissible ambient noise levels for audiometric test rooms. Acoustical Society of America, New York.
American National Standards Institute. (2019). S3.21, Methods for manual pure-tone threshold audiometry. Acoustical Society of America, New York.
Campo, P., Morata, T. C., & Hong, O. (2013). Chemical exposure and hearing loss. Disease-a-Month, 59(4), 119-138.
Dobie, R. A. (1983). Reliability and validity of industrial audiometry: Implications for hearing conservation program design. The Laryngoscope 93(7), 906–927.
Federal Highway Administration. (1994). Physical qualifications for drivers, 49 C.F.R. § 391.41. https://www.ecfr.gov/cgi-bin/retrieveECFR?gp=1&ty=HTML&h=L&mc=true&=PART&n=pt49.5.391#se49.5.391_141
Flamme, G. A., Deiters, K. K., Stephenson, M. R., Themann, C. L., Murphy, W. J., Byrne, D. C., Goldfarb, D. G., Zeig-Owens, R., Hall, C., Prezant, D. J., & Cone, J. E. (2020). Population-Based age adjustment tables for use in occupational hearing conservation programs. International Journal of Audiology, 59(sup1), S20−S30.
Federal Railroad Administration. (2006). Occupational noise exposure, 49 C.F.R. § 227. https://www.ecfr.gov/current/title-49/subtitle-B/chapter-II/part-227
Kerns, E., Masterson, E. A., Themann, C. L., & Calvert, G. M. (2018). Cardiovascular conditions, hearing difficulty, and occupational noise exposure within US industries and occupations. American Journal of Industrial Medicine, 61(6), 477–491.
Mahomed, F., Eikelboom, R. H., & Soer, M. (2013). Validity of automated threshold audiometry: A systematic review and meta-analysis. Ear and Hearing, 34(6), 745−752.
Meinke, D. K., & Martin, W. H. (2023). Boothless audiometry: Ambient noise considerations. The Journal of the Acoustical Society of America, 153(1), 26-39.
Mirza, R., Kirchner, D. B., Dobie, R. A., Crawford, J., & ACOEM Task Force on Occupational Hearing Loss. (2018). Occupational noise-induced hearing loss. Journal of Occupational and Environmental Medicine, 60(9), e498-e501.
Mine Safety and Health Administration. (1999). Occupational noise exposure, 30 C.F.R. § 62. https://www.govinfo.gov/content/pkg/FR-1999-09-13/pdf/99-22964.pdf#page=83
Mine Safety and Health Administration. (2000). Compliance guide to MSHA’s occupational noise exposure standard. U.S. Department of Labor Mine Safety and Health Administration. https://arlweb.msha.gov/REGS/COMPLIAN/GUIDES/noise/guide303.PDF
Murphy, W. J., Themann, C. L., & Murata, T. K. (2016). Hearing protector fit testing with off-shore oil-rig inspectors in Louisiana and Texas. International Journal of Audiology, 55(11), 688-698.
National Institute for Occupational Safety & Health. (1998). Criteria for a recommended standard: Occupational noise exposure, revised criteria 1998 (Report No 98-126). https://www.cdc.gov/niosh/docs/98-126/pdfs/98-126.pdf
Occupational Safety and Health Administration. (2002). Recording criteria for cases involving cccupational hearing loss, 29 C.F.R. § 1904.10. https://www.ecfr.gov/current/title-29/subtitle-B/chapter-XVII/part-1904/subpart-C/section-1904.10
Occupational Safety and Health Administration. (1983). Occupational noise exposure, 29 C.F.R. § 1910.95. https://www.ecfr.gov/current/title-29/subtitle-B/chapter-XVII/part-1910/subpart-G/section-1910.95
Rabinowitz, P. M., Galusha, D., Ernst, C. D., & Slade, M. D. (2007). Audiometric “early flags" for occupational hearing loss. Journal of Occupational and Environmental Medicine, 49(12), 1310-1316.
Rink, T. (1989). Clinical review of patterns from 300,000 industrial audiograms [Paper presentation pp. 12–14]. Industrial Hearing Conservation Conference, Lexington, KY.
Royster, J. D. (1992). Evaluation of different criteria for significant threshold shift in occupational hearing conservation programs, Final Report (No. PB-93-159143). Environmental Noise Consultants, Inc., Raleigh, NC.
Royster, J. D. (1996). Evaluation of additional criteria for significant threshold shift in occupational hearing conservation programs (No. PB-97-104392). Environmental Noise Consultants, Inc., Raleigh, NC.
U.S. Department of Defense. (2010, August 14). Hearing conservation program (DoD Instruction 6055.12). https://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodi/605512p.pdf
Meinke, D. (2023). 20Q: occupational audiometry. AudiologyOnline, Article 28524. Available at www.audiologyonline.com