- The Short Answer: What OHC Means Here
- Who Issues the Credential
- What an Occupational Hearing Conservationist Actually Does
- The Path From Course to COHC Designation
- How the Written Exam Is Built
- The Eleven Blueprint Headings Decoded
- Where These Professionals Work
- The Five-Year Clock: Renewal and Extensions
- The Acronym Trap: Why Context Matters
- Sequencing Your Preparation Around the Blueprint
- Frequently Asked Questions
- Here, OHC means Occupational Hearing Conservationist, a credential issued by CAOHC that awards the COHC designation.
- Certification requires a minimum 20-hour approved course, two practicums, and a written exam passed at 70% or higher.
- The initial exam runs on a 75-minute timer that cannot be paused, with four-option single-best-answer questions.
- Certification lasts five years; renewal needs an 8-hour course, both practicums, and a 30-question, 45-minute exam.
The Short Answer: What OHC Means Here
On this site, OHC stands for Occupational Hearing Conservationist. It describes a trained professional who carries out the practical, day-to-day work of an occupational hearing conservation program: testing workers' hearing, helping them choose and wear hearing protection, and keeping the records that show whether a program is actually protecting people from noise-induced hearing loss.
The word "conservationist" is doing real work in that title. Unlike an audiologist who diagnoses and treats hearing disorders, an Occupational Hearing Conservationist focuses on preventing occupational hearing loss and catching early changes in a worker's hearing before they become permanent disability. The role sits at the intersection of audiometry, noise measurement, regulatory compliance, and worker education.
If you have searched the acronym and landed on unrelated meanings, that is a common experience, and we address it directly later in this article. For deeper background on the credential itself, see our overview pages What Is OHC? and OHC Certification.
Who Issues the Credential
The certification is issued by the Council for Accreditation in Occupational Hearing Conservation (CAOHC). Passing the initial certification process earns you the COHC designation, which is the credential letters you use after your name. This article's scope is the initial Occupational Hearing Conservationist certification, not the separate CAOHC pathways for Course Director or Professional Supervisor of the Audiometric Monitoring Program (CPS/A) certification.
CAOHC publishes an OHC Handbook and Instructions (revised February 2023) that lays out what the certification covers, including an explicit exam blueprint on pages 6 to 8. Administration details come from CAOHC's Course Director Policies and Procedures Manual, most recently revised in November 2025. Because these are the primary documents, they are the ones worth reading yourself rather than relying on secondhand summaries.
What an Occupational Hearing Conservationist Actually Does
The certification exists because a workplace hearing conservation program has many hands-on tasks that need a trained person. A COHC-certified professional typically takes part in several of the following activities:
- Performing audiometric tests on employees, including baseline and annual tests, in a suitable testing environment.
- Explaining the test to the worker so the results are reliable and the worker understands what the test means.
- Checking the audiometer and the booth or room so that results reflect the worker's hearing rather than equipment or background-noise problems.
- Reviewing audiograms for changes over time that may signal developing noise-induced hearing loss and may need referral.
- Fitting hearing protection devices and verifying that workers can wear them correctly.
- Counseling and training employees about noise, hearing loss, and protection.
- Keeping records and coordinating with the other members of the hearing conservation team.
Notice how closely this list mirrors the exam blueprint. That is not a coincidence: the blueprint is built around the job. If you want to see how these duties translate into job postings, our page on OHC Jobs covers the employment side.
The Path From Course to COHC Designation
Certification is not an exam-only credential. It is a three-part requirement, and all three parts must be satisfied:
- A minimum 20-hour approved course. The course is delivered by an approved Course Director.
- Satisfactory practicums in both audiometric testing and hearing-protection fitting.
- The written exam, passed at the minimum standard.
- Components of an effective program
- How testing, protection, training, and records support each other
- Structures of the outer, middle, and inner ear
- How noise damages the cochlea
- Conditions that may warrant referral rather than routine monitoring
- Frequency, intensity, and the decibel scale
- Giving clear, consistent test instructions
- Which regulatory requirements trigger a program
- Why state rules can differ from federal ones
- Calibration and daily equipment checks
- Controlling background noise during testing
- Standard test procedure and response handling
- Recognizing unreliable responses
- Spotting shifts from baseline
- Deciding when follow-up or referral is appropriate
- Sound measurement concepts
- Engineering and administrative controls
- Types of HPDs and their trade-offs
- Fitting, insertion, and verification practice
- Communicating results sensitively
- Motivating consistent protection use
- What records must be maintained
- How the OHC works with the supervising professional, management, and workers
- Manufacturing plants with machinery, stamping, or assembly noise
- Construction and heavy industry, where mobile testing is common
- Oil, gas, mining, and utilities
- Military and defense-related employers
- Occupational health clinics and mobile testing companies that provide audiometric services to many employers
- Corporate safety and environmental health departments
- A minimum 8-hour refresher course
- Satisfactory completion of both practicums again
- A separate recertification exam of 30 questions with a 45-minute limit
- Hearing Conservation (Overall); Anatomy, Physiology and Diseases of the Ear
- Physics of sound and the decibel scale from Domain 3
- Audiometer and Testing Environment; Audiometric Techniques and Testing
- Audiometric Review and Evaluation, using sample audiograms
- Noise Measurement and Control; HPD Fitting
- Counseling and Training; Recordkeeping and the Hearing Conservation Team
- Federal and State Regulations, revisited with everything else in context
- Timed practice sets mimicking the 75-minute limit
One detail that surprises many people: there are no course-enrollment prerequisites. You do not need a particular degree or prior hearing-health credential just to sign up for the training. That makes the credential accessible to occupational health nurses, safety professionals, technicians, and others who have been handed responsibility for a hearing conservation program. Our guide to OHC Requirements walks through eligibility in more depth, and OHC Training covers what to expect in the classroom portion.
How the Written Exam Is Built
The written exam uses four-option, single-best-answer multiple-choice questions. "Single best answer" matters: more than one option may look defensible, and you are expected to choose the one that is most correct under standard occupational hearing conservation practice. The exam is available in English or Spanish.
| Feature | Initial Certification | Recertification |
|---|---|---|
| Course requirement | Minimum 20-hour approved course | Minimum 8-hour course |
| Practicums | Audiometric testing and HPD fitting | Both practicums |
| Exam timer | 75 minutes | 45 minutes |
| Question format | Four-option, single best answer | 30 questions |
| Minimum passing mark | 70% | See CAOHC recertification guidance |
The question-count discrepancy
You may see conflicting numbers online for how many questions the initial exam contains. CAOHC's own handbook cites 55 questions, while the CAOHC online exam guide cites 50. We do not try to reconcile these or guess which includes unscored items, because the sources do not explain the difference. The practical takeaway is to prepare for the full blueprint rather than to optimize around a specific question count, and to confirm current details with your Course Director.
Timer and navigation rules
The exam timer cannot be paused. You can, however, flag questions and return to them, which makes a two-pass approach sensible: answer what you know, flag what you do not, and use remaining time on the flagged items. CAOHC's certification exam instructions document explains the interface.
Passing score and attempts
The minimum passing mark is 70%. You are allowed a maximum of three attempts. Retakes are arranged through your Course Director within 30 days of the preceding attempt, and proctoring fees may apply. Details on scoring are in OHC Passing Score, and the money side is covered in OHC Certification Cost. Because tuition is set by Course Directors rather than a single national price, treat any quoted figure as something to verify with the specific course you choose.
Key Takeaway
Three attempts within a tight retake window means your first attempt should be a serious one. Plan to sit the exam while course material is fresh, and talk to your Course Director up front about how retakes would be scheduled.
The Eleven Blueprint Headings Decoded
CAOHC's handbook lists eleven headings and labels them an exam blueprint. Importantly, the percentages are omitted, so there is no officially supported "heaviest" domain. Anyone claiming one domain is worth a specific percentage is guessing. Study all eleven. Here is what each one asks of you in practical terms.
1. Hearing Conservation (Overall)
The big-picture framework: why programs exist and how the pieces fit together.
2. Anatomy, Physiology and Diseases of the Ear
You need enough ear science to recognize what noise does and what is not noise-related.
3. Hearing and the Physics of Sound and Performing and Explaining a Hearing Test
Core acoustics paired with test delivery and worker communication.
4. Federal and State Regulations Related to Occupational Noise-Induced Hearing Loss
The legal backbone of workplace hearing programs.
5. Audiometer and Testing Environment
Reliable data starts with a reliable instrument and a quiet enough space.
6. Audiometric Techniques and Testing
The hands-on method of obtaining thresholds.
7. Audiometric Review and Evaluation
Reading audiograms and comparing them to prior results.
8. Noise Measurement and Control
Understanding the noise source, not just its effect on ears.
9. Hearing Protection Device (HPD) Fitting
Proper fit is what makes protection work in real life.
10. Counseling and Training
Educating workers so they actually use what you give them.
11. Recordkeeping and the Hearing Conservation Team
Documentation and roles across the program.
For a section-by-section treatment, see our complete guide to all 11 content areas, and keep the OHC Cheat Sheet handy for a compact review.
Where These Professionals Work
Hearing conservation programs exist wherever workers face hazardous noise, so the credential travels across industries. Common settings include:
Some COHC holders are full-time hearing conservation staff; others hold the credential as one part of a broader safety or nursing role. Whether the credential pays off depends heavily on that context, which we cover in Is the OHC Certification Worth It? and OHC Salary Guide. We deliberately avoid quoting specific earnings here because they vary by region, industry, and whether the credential is your main job function.
The Five-Year Clock: Renewal and Extensions
Certification is valid for five years from course completion. To renew, you need:
If you cannot finish renewal on time, you can request an extension, but you must do so at least 30 days before your certification expires. Missing that window is an avoidable mistake. Put your expiry date and a 60-day reminder on your calendar the day you pass. CAOHC's FAQ and recertification pages are the authoritative references for current renewal handling.
The Acronym Trap: Why Context Matters
"OHC" is a crowded acronym. A quick search can return results about completely unrelated credentials, medical terms, and industry programs that happen to share the same three letters. Their requirements, costs, and exam rules have nothing to do with the CAOHC certification described here.
When you evaluate any source, check three things: Does it name CAOHC as the issuer? Does it mention the COHC designation? Does it describe a 20-hour course with audiometric and hearing-protection practicums? If not, you are likely reading about something else. Our related explainers, What Does OHC Stand For?, OHC Meaning, and What Is OHC Certification?, keep the focus on the hearing conservation meaning.
Sequencing Your Preparation Around the Blueprint
Because no domain weights are published, the sensible approach is balanced coverage with extra time on the topics that feel least natural to you. One way to order the work, assuming you are studying alongside or just after the approved course:
Foundations
Testing Core
Protection and People
Regulations and Rehearsal
Regulations come late deliberately: the rules make far more sense once you understand what audiometry, noise measurement, and recordkeeping actually involve. Full planning advice is in the OHC Study Guide, and you can test yourself with the OHC practice tests on our main site. For a sense of what to expect, read How Hard Is the OHC Exam? and OHC Pass Rate; note that we do not cite a specific pass percentage because no verified figure is available to us.
If you are ready to see how you perform against four-option, single-best-answer questions, start with a full practice session and review every miss against the eleven blueprint headings. Scheduling specifics, including testing windows, live with your Course Director, as described in OHC Exam Dates.
Frequently Asked Questions
OHC means Occupational Hearing Conservationist. It refers to a professional trained to test workers' hearing, fit hearing protection, counsel employees, and keep records within a workplace hearing conservation program. Passing CAOHC certification awards the COHC designation. See also What Is A OHC?.
The Council for Accreditation in Occupational Hearing Conservation (CAOHC) issues it. Courses are taught by approved Course Directors, who also handle tuition and registration for their sessions.
No. There are no course-enrollment prerequisites. However, certification itself requires completing a minimum 20-hour approved course, passing both the audiometric and hearing-protection-fitting practicums, and passing the written exam at 70% or higher.
It is valid for five years from course completion. Renewal requires a minimum 8-hour course, both practicums, and a separate 30-question, 45-minute recertification exam. Request any extension at least 30 days before expiry.
A maximum of three attempts is allowed. Retakes are arranged with your Course Director within 30 days of the preceding attempt, and proctoring fees may apply. Confirm exact costs with your course provider.