- What the Credential Actually Is
- Who Issues It and How the Process Works
- The Path: Course, Practicums, and Written Exam
- Exam Format at a Glance
- The Eleven Blueprint Headings
- Attempts and Retakes
- The Five-Year Cycle and Recertification
- Who Needs This Credential
- Sequencing Your Preparation
- Avoiding Scope Confusion
- Frequently Asked Questions
- OHC here means Occupational Hearing Conservationist, awarded as the COHC designation by CAOHC after training and a written exam.
- Certification requires a minimum 20-hour approved course, audiometric and hearing-protection-fitting practicums, and a passing written exam.
- The initial exam is four-option multiple choice with a 75-minute timer, a 70% minimum, and English or Spanish versions.
- You get a maximum of three attempts, and retakes are arranged with your Course Director within 30 days of the previous attempt.
What the Credential Actually Is
The Occupational Hearing Conservationist credential certifies that a person has been trained and tested to carry out the hands-on work of an occupational hearing conservation program. That work includes performing and explaining hearing tests, fitting hearing protection devices, counseling employees, and keeping the records that make a program defensible. Successful candidates earn the COHC designation.
If you landed here searching for what the letters mean, our short explainers on what OHC stands for and the meaning of OHC cover the terminology. This article focuses on the certification itself: who awards it, what it takes to earn it, and what the exam covers. The broader overview lives at OHC Certification.
Who Issues It and How the Process Works
The credential is issued by the Council for Accreditation in Occupational Hearing Conservation (CAOHC). CAOHC does not run a walk-in testing-center model. Instead, certification is tied to an approved training course taught by a CAOHC-certified Course Director.
That structure has practical consequences:
- Your Course Director is your point of contact. Tuition and course registration are handled by the Course Director, not through a central CAOHC checkout.
- The exam is administered through the CAOHC Learning Center by the Course Director or an approved proctor.
- Policies are published, and they change. The Course Director Policies and Procedures Manual (revised November 2025) is the current administration reference, while the OHC Handbook and Instructions (revised February 2023) defines the exam blueprint scope.
Because fees vary by course provider, check the details in our OHC certification cost breakdown and confirm pricing directly with whichever Course Director is teaching your class.
The Path: Course, Practicums, and Written Exam
There are no course-enrollment prerequisites, so you do not need a prior degree or hearing-health credential to sign up for an approved course. What the certification itself requires is a three-part sequence:
- A minimum 20-hour approved course. This is instructional time, and it is separate from the exam timer.
- Satisfactory practicums. You must demonstrate competence in both audiometric testing and hearing-protection fitting under observation.
- The written exam. A passing score on the multiple-choice exam completes the requirement.
For a fuller eligibility walk-through, see OHC requirements and how to qualify.
Exam Format at a Glance
| Feature | Initial OHC Exam |
|---|---|
| Question type | Four-option, single-best-answer multiple choice |
| Time limit | 75 minutes; the timer cannot be paused |
| Minimum score | 70% |
| Languages | English or Spanish |
| Navigation | Questions can be flagged and revisited |
| Administration | CAOHC Learning Center, via Course Director or approved proctor |
| Maximum attempts | Three |
The question-count discrepancy
You will see two different question counts in CAOHC's own materials. The handbook lists 55 questions, while the online exam guide lists 50. We have not found an official explanation for the difference, and it would be a guess to say that unscored questions account for it. For that reason this article does not commit to a single number. Ask your Course Director which version of the exam applies to your session, and read the official certification exam instructions before test day.
The 70% minimum is spelled out in more detail in our guide to the OHC passing score. Because the timer cannot be paused, practice working at a steady pace; the flag-and-return feature is your main tool for handling questions that stall you.
The Eleven Blueprint Headings
The OHC Handbook and Instructions (pages 6-8) lists eleven content headings under the label of an exam blueprint. The handbook does not publish percentage weights for them. That means no one can honestly tell you which domain is "the heaviest," and any prep resource claiming exact weights is going beyond the official source. Treat all eleven as fair game.
For a deeper domain-by-domain treatment, read our complete guide to all 11 OHC content areas. Here is how the headings group in practice.
Foundations: the program, the ear, and the physics
Domain 1: Hearing Conservation (Overall)
The big-picture rationale for hearing conservation programs and how their components fit together.
- Why occupational noise exposure harms hearing and why prevention is the goal
- How monitoring, testing, protection, and training work as one system
Domain 2: Anatomy, Physiology and Diseases of the Ear
The structure and function of the outer, middle, and inner ear, plus common conditions.
- How sound travels from the ear canal to the cochlea
- Distinguishing noise-induced damage from other causes of hearing loss
Domain 3: Hearing and the Physics of Sound and Performing and Explaining a Hearing Test
Core acoustics paired with the practical skill of administering and explaining a test.
- Frequency, intensity, and the decibel scale
- Describing a hearing test to an employee in plain language
Rules, equipment, and technique
Domain 4: Federal and State Regulations Related to Occupational Noise-Induced Hearing Loss
The regulatory framework that makes hearing conservation programs mandatory in many workplaces.
- What triggers program requirements
- How state rules may differ from federal expectations
Domain 5: Audiometer and Testing Environment
The equipment and conditions behind valid test results.
- Calibration and daily checks
- Ambient noise in the test space and why it matters
Domain 6: Audiometric Techniques and Testing
The mechanics of obtaining accurate thresholds.
- Instructing the test subject and positioning the headphones
- Recognizing unreliable responses during testing
Domain 7: Audiometric Review and Evaluation
Interpreting results and deciding what happens next.
- Comparing a current audiogram to a baseline
- Recognizing when a result calls for follow-up or referral
Control, protection, and program management
Domain 8: Noise Measurement and Control
Quantifying noise exposure and reducing it at the source where possible.
- Sound level meters and dosimetry concepts
- The logic of engineering and administrative controls before relying on personal protection
Domain 9: Hearing Protection Device (HPD) Fitting
Selecting, fitting, and verifying protection so it works in real use.
- Fit differences across earplugs and earmuffs
- Why a poorly fitted device delivers far less protection than its label suggests
Domain 10: Counseling and Training
Communicating with employees so they actually change behavior.
- Explaining results without alarming or dismissing the employee
- Motivating consistent HPD use
Domain 11: Recordkeeping and the Hearing Conservation Team
Documentation and the roles of the people who share responsibility for the program.
- What records must be maintained and for whom
- How the conservationist, supervisor, employer, and employee each contribute
Key Takeaway
Domains 3, 5, 6, and 9 mirror the two practicums (audiometric testing and HPD fitting). Hands-on practice in class reinforces the written material in those areas, so treat practicum time as exam preparation, not a separate hurdle.
Attempts and Retakes
You are allowed a maximum of three attempts at the initial written exam. If you do not pass, the retake is arranged through your Course Director, and it must take place within 30 days of the preceding attempt. Retakes may carry proctoring fees, so ask about them up front rather than discovering them after a disappointing result.
Two takeaways follow from this. First, the 30-day window is short, which means a failed first attempt should trigger immediate, targeted review rather than a long pause. Second, because attempts are limited, it is worth arriving at the first sitting well prepared. Our difficulty guide discusses what tends to make the exam challenging, and our pass rate article explains what is and is not known about outcomes.
The Five-Year Cycle and Recertification
The credential is valid for five years from course completion. Staying certified is not just a matter of paying a fee; it requires showing continued competence.
| Element | Initial Certification | Recertification |
|---|---|---|
| Course | Minimum 20 hours | Minimum 8 hours |
| Practicums | Audiometric and HPD fitting | Both practicums again |
| Written exam | 75 minutes, 70% minimum | Separate exam: 30 questions, 45 minutes |
| Validity | Five years from course completion | Renewed cycle |
If you cannot complete recertification in time, an extension can be requested, but it should be requested at least 30 days before your expiry date. Details are on CAOHC's recertification page and its FAQ. Put your expiry date on a calendar the day you pass.
Who Needs This Credential
Hearing conservation work shows up wherever employees are exposed to hazardous noise. Typical settings include manufacturing plants, construction and heavy industry, mining, utilities, transportation, and military or government facilities. The people who hold the credential tend to be occupational health nurses, safety and industrial hygiene staff, audiometric technicians, and employees designated to run an in-house hearing conservation program.
Some employers require the credential outright for anyone who administers audiometric tests; others value it as evidence that testing and fitting are being done to a recognized standard. For a closer look at the job market, see OHC jobs. If you are weighing earnings and payoff, our salary guide and ROI analysis take a measured, evidence-based approach and avoid invented figures.
Sequencing Your Preparation
Because the exam follows an in-person or proctored course, the best preparation starts before class and continues after it. Here is one way to align your reading with the eleven headings. For a complete method, use our OHC study guide.
Build the vocabulary
- Skim Domains 2 and 3 so ear anatomy and basic acoustics are familiar
- Read the handbook's blueprint pages so you know all eleven headings
Treat practicums as study time
- Focus on Domains 5, 6, and 9 while handling the equipment
- Ask your Course Director how local and state rules apply (Domain 4)
Close the gaps
- Review Domains 7, 8, 10, and 11, which are easy to underestimate
- Take a timed practice set on the OHC practice test to rehearse the 75-minute pace
Keep your review notes brief and organized by domain. The OHC cheat sheet is useful for a final pass the night before, though it is a supplement to the course and not a replacement for it. Also be aware that we did not use paid third-party study-guide contents to construct the blueprint described here; it comes from CAOHC's own published handbook.
Avoiding Scope Confusion
The acronym causes real confusion online, and CAOHC has several related programs. To keep your search clean:
- COHC (what this article covers): initial Occupational Hearing Conservationist certification through a 20-hour approved course.
- CPS/A: a separate supervisory-level CAOHC credential with its own prerequisites.
- Course Director: the instructor-level certification held by the person who teaches your course and administers your exam.
If you are still orienting yourself, our explainers on what OHC is, what an OHC is, and what OHC means address the common questions. Practice questions built around the correct credential are available on the main practice test site.
Frequently Asked Questions
OHC stands for Occupational Hearing Conservationist. Candidates who complete the approved course, the practicums, and the written exam earn the COHC designation from the Council for Accreditation in Occupational Hearing Conservation (CAOHC).
No. There are no course-enrollment prerequisites. Certification itself requires a minimum 20-hour approved course, satisfactory audiometric and hearing-protection-fitting practicums, and a passing score on the written exam.
The initial written exam runs 75 minutes and uses four-option, single-best-answer multiple choice. You need at least 70% to pass. The timer cannot be paused, but you can flag questions and return to them.
CAOHC's own materials disagree: the handbook lists 55 questions and the online exam guide lists 50. Ask your Course Director which applies to your session, and check the exam instructions published by CAOHC.
You may attempt the exam a maximum of three times, with retakes arranged through your Course Director within 30 days of the previous attempt. Certification is valid for five years from course completion and is renewed with an 8-hour course, both practicums, and a separate 30-question, 45-minute exam.