Occupational Hearing Conservation Glossary

The OSHA threshold at which employers must establish a Hearing Conservation Program: an 8-hour time-weighted average (TWA) of 85 dBA. Employee exposures are measured without regard to the attenuation provided by hearing protectors. (29 CFR 1910.95(c)(1))

Workplace schedule or procedural modifications designed to reduce the duration of employee noise exposure — such as rotating job assignments or limiting time in high-noise areas. Administrative controls are secondary to engineering controls in the hierarchy of noise hazard mitigation.

Real-time measurement of background sound pressure levels in an audiometric testing environment to confirm that noise does not exceed OSHA Maximum Permissible Ambient Noise Levels (MPANLs). Required when testing outside a traditional sound booth. Ambient noise records must be maintained as part of the audiometric record. (29 CFR 1910.95 Appendix D)

SHOEBOX: SHOEBOX PureTest performs an automated room scan before each session using an external Class 2 microphone, measuring against OSHA Appendix D limits.

A complete audiometric evaluation obtained at least once per year for every employee whose noise exposure equals or exceeds the action level. Compared against the baseline audiogram to identify standard threshold shifts. (29 CFR 1910.95(g)(6))

SHOEBOX: SHOEBOX PureTest performs annual audiograms on-site; the Data Management Portal (PLUS tier) tracks due-for-testing status per employee.

A licensed audiologist or physician who reviews individual employee audiograms for clinical significance, confirms or denies threshold shifts, identifies problem audiograms, recommends follow-up actions, and determines work-relatedness of hearing changes. In most jurisdictions, must be licensed in the state where reviewed employees are located.

SHOEBOX: SHOEBOX Audiological Services provides a multi-state network of licensed Audiology Reviewers who complete reviews through the Data Management Portal.

An enclosure engineered to maintain interior sound pressure levels below OSHA Maximum Permissible Ambient Noise Levels (MPANLs), providing a controlled acoustic environment for hearing threshold testing. OSHA requires MPANLs to be met; a booth is one means of achieving this but is not explicitly mandated. (29 CFR 1910.95(h)(4) and Appendix D)

The measurement of an individual’s hearing thresholds across a range of frequencies using calibrated equipment following standardized protocols. In occupational hearing conservation, refers specifically to pure tone, air conduction threshold testing at OSHA-required frequencies. (29 CFR 1910.95(h)(1))

SHOEBOX: SHOEBOX PureTest is an iPad-based audiometric testing platform that performs OSHA-compliant pure tone air conduction testing in boothless environments.

The foundational audiometric measurement against which all subsequent audiograms are compared for STS detection. Must be preceded by at least 14 hours without workplace noise exposure. Must be established within 6 months of an employee’s first exposure at or above the action level (12 months for mobile van programs, with HPD use required during the gap). (29 CFR 1910.95(g)(5))

SHOEBOX: SHOEBOX Data Management PLUS manages baseline assignment and revision per employee, with triage routing to Audiology Reviewers when revision is indicated.

A daily functional check of audiometer performance in which a person with known stable hearing thresholds tests the audiometer at all configured frequencies and compares results against their personal baseline. A deviation of 10 dB or more at any frequency requires acoustic calibration. Satisfies OSHA’s requirement for a functional operation check before each day’s use. (29 CFR 1910.95(h)(5)(i))

SHOEBOX: SHOEBOX PureTest’s daily calibration workflow guides the examiner through the biological verification step and logs the result as compliance documentation.

An audiometric technician who has completed the Council for Accreditation in Occupational Hearing Conservation (CAOHC) 20-hour initial certification course and maintains 5-year recertification through an 8-hour refresher. CAOHC certification is the recognized industry standard for occupational audiometric technicians. Certification is not required for technicians operating microprocessor audiometers, though the professional responsibility requirement still applies. (29 CFR 1910.95(g)(3))

Physical modifications to equipment, processes, or work environments designed to reduce noise at its source or along its transmission path — the preferred intervention in the hierarchy of noise hazard control. Examples include replacing mechanical components with quieter electronic equivalents, installing sound-absorbing materials, and enclosing noise-generating equipment.

The relationship between noise level and permissible exposure duration. OSHA uses a 5 dB exchange rate: each 5 dB increase above the PEL halves the permissible exposure duration. NIOSH recommends a 3 dB exchange rate. Content must always specify which exchange rate is being referenced. (29 CFR 1910.95, Table G-16)

Centralized administration of multiple audiometric testing devices from a single management interface.

SHOEBOX: In SHOEBOX, fleet management allows administrators to pre-configure test settings, lock configurations to prevent deviation, enforce daily calibration steps across all devices, and synchronize employee data across a testing program.

The complete set of employer-administered activities required by OSHA to protect noise-exposed workers from hearing loss: noise exposure monitoring, audiometric testing, hearing protector provision, annual training, and recordkeeping. Required for all employees exposed to 85 dBA TWA or above. (29 CFR 1910.95(c)(1))

Any device worn in or over the ear to reduce the level of sound reaching the eardrum. Must be provided at no cost to employees exposed to 85 dBA TWA or above. Employees must be offered a selection from a variety of suitable HPDs. Real-world attenuation is typically well below the labeled NRR. (29 CFR 1910.95(i))

The Health Insurance Portability and Accountability Act. Establishes federal privacy and security requirements for individually identifiable health information. Audiometric records are protected health information subject to HIPAA when maintained by covered entities or business associates.

An occupational health professional who identifies, evaluates, and controls chemical, physical, ergonomic, and biological workplace hazards. In hearing conservation, Industrial Hygienists conduct noise surveys using sound level meters and dosimeters, build noise exposure maps, and establish personal exposure assessments that determine which employees must be enrolled in the Hearing Conservation Program.

The maximum octave-band sound pressure levels that may be present in an audiometric testing environment without compromising the validity of hearing threshold measurements. Specified in 29 CFR 1910.95 Appendix D. The basis for room scan pass/fail determination in boothless audiometric testing. (29 CFR 1910.95 Appendix D)

A standardized ascending audiometric test protocol used to determine hearing thresholds. The examiner (or automated system) presents tones at decreasing levels until the subject no longer responds, then increases in 5 dB steps until a threshold is confirmed at the lowest level at which the subject responds at least 50% of the time. The required protocol for OSHA-compliant audiometric testing.

SHOEBOX: SHOEBOX PureTest’s automated testing mode runs the Modified Hughson-Westlake protocol without examiner intervention.

A personal noise dosimeter measures an individual worker’s cumulative noise exposure throughout a work shift, expressed as a percentage of the permissible daily dose. A dose of 100% equals the PEL (90 dBA for 8 hours). A dose of 50% equals the action level (85 dBA for 8 hours). Dosimetry is a primary tool for determining which employees must be enrolled in the Hearing Conservation Program.

A sensorineural hearing loss resulting from damage to the hair cells of the cochlea caused by excessive noise exposure. NIHL is permanent and irreversible — damaged cochlear hair cells do not regenerate. Audiometrically, NIHL typically presents as a notch in the 3,000 to 6,000 Hz range, most pronounced at 4,000 Hz.

The adjustment applied to the manufacturer’s labeled Noise Reduction Rating (NRR) to estimate real-world attenuation. OSHA derates using (NRR – 7) / 2. NIOSH applies variable derating by protector type: 75% of NRR for earmuffs, 50% for formable earplugs, 30% for all other earplugs. Content must specify which method is applied when citing attenuation estimates.

OSHA’s injury and illness recordkeeping form (Form 300). Hearing loss is recordable when an employee has experienced an STS AND their hearing level at 2,000, 3,000, and 4,000 Hz is 25 dB or more above audiometric zero in the same ear. Must be posted publicly in February for the preceding year. Companies with 10 or fewer employees are generally exempt. (29 CFR 1904.10)

Chemical substances that are toxic to the structures of the inner ear and can cause hearing loss independently or synergistically with noise exposure. Common ototoxicants include organic solvents (toluene, styrene, xylene), heavy metals (lead, mercury), and certain pharmaceuticals. More than 30 million U.S. workers are exposed to potentially ototoxic chemicals in the workplace. OSHA’s noise standard does not explicitly address ototoxic exposures.

OSHA’s maximum allowable occupational noise exposure: 90 dBA as an 8-hour time-weighted average. When the PEL is exceeded, feasible engineering and administrative controls must be implemented to reduce exposure. Distinct from the action level (85 dBA), which triggers Hearing Conservation Program enrollment. (29 CFR 1910.95(a), Table G-16)

Age-related sensorineural hearing loss that progresses gradually with aging, predominantly affecting high frequencies. Presbycusis can confound occupational STS determinations in older workers. OSHA allows (but does not require) age correction using Appendix F tables when calculating STS. Age correction is not permitted in Oregon or Washington for OSHA compliance purposes. Age correction cannot be applied when evaluating whether the 25 dB recordable threshold is met.

An audiogram that requires professional review beyond routine STS detection, because the results indicate a possible clinical pathology, testing validity concerns, or need for further evaluation. Problem audiograms may show: sudden drops in hearing, asymmetric loss, audiometric patterns inconsistent with noise exposure, or evidence of non-occupational pathology. The determination of what constitutes a problem audiogram is a clinical judgment, not a software rule. (29 CFR 1910.95(g)(7)(iii))

SHOEBOX: The SHOEBOX Data Management Portal’s triage system automatically flags problem audiograms and routes them to the Audiology Review Network queue.

The audiologist, otolaryngologist, or physician with program-level responsibility for overseeing the audiometric testing component of a Hearing Conservation Program. Responsibilities include: ensuring testing environment adequacy, procedures, and recordkeeping; technician training; coordinating audiometric services; and annual review of program compliance. Required under 29 CFR 1910.95(g)(3). Distinct from the Audiology Reviewer, who has patient-level rather than program-level responsibility.

SHOEBOX: SHOEBOX Audiological Services provides CAOHC-certified Professional Supervisors as a managed service for organizations that do not have this role in-house.

The standard method of measuring hearing thresholds by presenting tones of specific frequencies at controlled intensities and recording the quietest level at which the subject can reliably detect the tone. Required test method under OSHA’s occupational hearing standard. Testing must cover 500, 1,000, 2,000, 3,000, 4,000, and 6,000 Hz per ear, per 29 CFR 1910.95(h)(1).

SHOEBOX: SHOEBOX PureTest performs pure tone air conduction audiometry using the Modified Hughson-Westlake protocol across all OSHA-required frequencies.

SHOEBOX PureTest’s integrated system of continuous ambient noise monitoring and response validity checking that operates throughout the audiometric testing session to protect result integrity. REACT™ Safeguards combines two mechanisms: (1) real-time ambient noise monitoring against OSHA or ANSI MPANLs, with configurable alerts that can pause the test, notify the examiner after completion, or log the data without interruption; and (2) the Response Wizard, which monitors employee response patterns during automated testing and alerts the examiner when anomalies — such as catch-tone failures or irregular response timing — indicate that results may not reflect actual hearing thresholds.

Together, these mechanisms address the two primary sources of invalid audiometric results in boothless environments: environmental noise interference and unreliable subject responses. REACT™ Safeguards operates offline and in all testing modes.

The employer’s obligation to maintain accurate and accessible records of employee noise exposure assessments and audiometric tests. Audiometric test records must be retained for the duration of employment (29 CFR 1910.95(m)(3)(ii)). Noise exposure measurement records must be retained for 2 years (29 CFR 1910.95(m)(3)(i)). Records must include: employee name and job classification, audiogram date, examiner name, date of last calibration, most recent noise exposure assessment, and background sound pressure levels in the test room.

SHOEBOX: The SHOEBOX Data Management Portal stores the complete required record set with automatic backup from iPads, accessible on demand without vendor-mediated records requests.

A SHOEBOX PureTest feature — one component of REACT™ Safeguards — that monitors response patterns during automated testing and alerts the test examiner when anomalies are detected, such as unreliable response patterns, catch-tone failures, or unlikely thresholds, enabling corrective action before the test concludes.

Hearing loss caused by damage to the cochlea (sensory hair cells) or the auditory nerve. Sensorineural hearing loss is the type produced by noise exposure and is permanent and irreversible. Distinguished from conductive hearing loss, which involves the outer or middle ear and is often medically treatable.

An average change in hearing threshold of 10 dB or more at 2,000, 3,000, and 4,000 Hz in either ear, measured relative to the baseline audiogram. The STS is the primary clinical and compliance threshold in occupational audiometry. An STS triggers: written employee notification within 21 days (29 CFR 1910.95(g)(8)(i)); HPD refitting and retraining; and, if the STS is work-related and the employee’s total hearing level at those frequencies is 25 dB or more above audiometric zero, recording on the OSHA 300 Log (29 CFR 1904.10(a)). (29 CFR 1910.95(g)(10)(i))

SHOEBOX: SHOEBOX PureTest automatically calculates STS against established baselines using OSHA and MSHA methodologies immediately upon test completion.

A short-term reduction in hearing sensitivity following noise exposure that recovers within 14 to 48 hours. TTS is distinct from permanent threshold shift. The 14-hour quiet period required before baseline audiograms is designed to allow TTS to fully resolve, ensuring the baseline reflects true resting hearing thresholds rather than temporary post-exposure depression.

A measure of an employee’s average noise exposure over an 8-hour work shift, accounting for varying noise levels at different times. Used to determine action level and PEL compliance. OSHA TWA is calculated using a 5 dB exchange rate; NIOSH REL uses a 3 dB exchange rate. (29 CFR 1910.95(c))

An employer-administered annual program for all employees exposed to noise at or above the action level. Required training content: (1) effects of noise on hearing; (2) the purpose of HPDs, their advantages and disadvantages, available types, and instruction in selection, fitting, use, and care; (3) the purpose of audiometric testing and an explanation of test procedures. Training must be updated when changes occur in protective equipment or work processes. (29 CFR 1910.95(k))