Policy
Noise-induced hearing loss (NIHL) resulting from occupational exposure to noise is recognized as an occupational disease under the Workers’ Compensation Act, Revised Statutes of Ontario, 1990, and the Workplace Safety and Insurance Act, 1997. Workers with NIHL due to the nature of their employment are entitled to benefits.
Purpose
The purpose of this policy is to:
- recognize NIHL as an occupational disease,
- establish initial entitlement guidelines to support timely and consistent adjudication of NIHL claims involving sufficient occupational exposure to noise, and
- provide additional guidance on entitlement to health care and non-economic loss (NEL) benefits in allowed NIHL claims.
Guidelines
Definitions
In this policy,
audiogram means a graph that displays the results of a pure tone hearing test. An audiogram shows the level, pattern, and type of hearing loss (i.e., sensorineural, conductive).
audiologist means a regulated health professional, registered with the College of Audiologists and Speech-Language Pathologists of Ontario, whose scope of practice includes assessing hearing function and prescribing and fitting hearing aids and other hearing assistive devices.
A-weighted decibel (dBA) means decibels measured using a sound level meter equipped with an A-weighting filter. A-weighting adjusts for the sensitivity of the human ear by de-emphasizing low frequencies, providing a single number measure of sound levels that reflects how sound is actually experienced or perceived.
decibel (dB) means a unit of measurement of sound.
hearing assessment means an evaluation of a person’s hearing, conducted at a health facility by a qualified healthcare provider, which includes a review of the person’s medical history, the administration of hearing tests, and any additional tests or procedures required to inform the presence, nature, and level of hearing loss.
hearing loss means a reduced acuity to hear sounds at or greater than 26.25 dB in each ear, as determined by an average hearing threshold calculated across the four key speech frequencies of 500 hertz (Hz), 1000 Hz, 2000 Hz, and 3000 Hz.
hearing protection devices (HPDs) means personal protective equipment worn by a person (e.g., ear plugs, earmuffs), and the use of engineering controls (e.g., sound-reducing booths or baffles) to help protect against noise.
noise exposure threshold (NET) means the combination of the time-weighted average occupational noise exposure, measured in dBA over an 8-hour workday, and cumulative duration of exposure (in years) that is generally sufficient to establish a causal link with NIHL.
noise-induced hearing loss (NIHL) means a permanent bilateral sensorineural hearing loss which may be symmetrical or asymmetrical, and which may include mixed hearing loss comprised of both sensorineural and conductive loss.
tinnitus means a symptom typically experienced as a sensation of ringing, whistling, buzzing, whooshing, or humming.
Standard of proof in NIHL claims
The standard of proof that applies to all issues under this policy is balance of probabilities. Applying this standard, the decision-maker must be satisfied, based on the available evidence that something is more likely than not to be true.
In NIHL claims, the decision-maker applies the standard of proof by gathering and assessing all available evidence relevant to the issue(s), including the worker’s medical history, hearing assessments, past and current audiograms, employment and exposure history. The decision-maker then weighs this evidence to make findings of fact based on balance of probabilities.
If the evidence for and against an issue is evenly balanced, the decision-maker must resolve the issue in favour of the person claiming benefits. For more information, refer to 11-01-13, Benefit of Doubt.
The standard of proof and benefit of doubt apply to each issue under consideration rather than the initial entitlement decision or any other subsequent benefit entitlement decision.
Work-relatedness in NIHL claims for initial entitlement
For all initial entitlement decisions, the NIHL must be determined to be work-related, and therefore is due to the nature of one or more employments in which the worker was engaged.
The test for determining work-relatedness is whether it is more likely than not that the worker’s exposure to noise during a specific covered period(s) of employment with an employer was a significant contributing factor in the development of their NIHL.
In situations where there is more than one period of employment (with more than one employer) but not enough occupational exposure with any single employer to determine work-relatedness, the decision-maker considers whether the worker’s cumulative exposure to noise in all those covered employment periods combined was a significant contributing factor in the development of the worker’s NIHL.
It is not necessary for the worker’s occupational exposure to be the sole, primary, or predominant cause of the NIHL to allow the claim for initial entitlement. When it is established that the occupational exposure has significantly contributed to the development of the NIHL, there can be entitlement even if there is also a history of non-occupational noise exposure and/or the presence of other non-work-related contributing factors.
Hearing assessments used for decision-making
The decision-maker will assess every hearing assessment submitted to determine whether the information is sufficient for decision-making. They may accept the assessment or determine that the assessment cannot be used for a NIHL determination.
Hearing assessments conducted on/after October 7, 2026
Any hearing assessment conducted on or after October 7, 2026, must be a complete assessment which includes both air and bone conduction testing. The hearing assessment, including any associated audiogram, must be completed in accordance with the practice standards of the applicable regulatory college or the healthcare provider’s recognized association.
Hearing assessments should be reported using the WSIB’s Hearing assessment, which includes hearing test results. Hearing assessments not submitted using the WSIB’s standardized form may be acceptable if they contain the same required information.
If any hearing assessment or audiogram submitted is incomplete or non-compliant with the specific instructions of the WSIB’s Hearing assessment, the decision-maker may return the documents to the health provider and request proper completion.
Overview of the evidentiary requirements for initial entitlement
Initial entitlement will generally be allowed when all three of the following evidentiary requirements are satisfied:
1. The worker has hearing loss
The worker’s average hearing level must be 26.25 dB or greater in each ear for a worker to have hearing loss.
2. The hearing loss is consistent with NIHL
The worker has permanent bilateral sensorineural (includes mixed) hearing loss which is either symmetrical (affecting both ears equally) or has an asymmetry (affecting one ear more than the other) that is consistent with NIHL.
3. The NIHL is due to occupational noise exposure
The worker’s occupational exposure to noise that meets the NET is generally sufficient to have significantly contributed to the development of the NIHL. The NET is where the worker was exposed to:
- a time-weighted average occupational noise level of 90 dBA, measured over an 8-hour workday, for a cumulative duration of at least 5 years, or
- a combination of occupational noise level (dBA, 8-hour time-weighted average) and cumulative duration of exposure (in years) that is equivalent.
If the worker’s exposure falls below the NET, the decision-maker assesses the totality of the evidence to determine whether sufficient work-related exposure can be established.
Exceptional considerations
In all cases, where a specialist in otolaryngology provides a diagnosis indicating that a worker’s hearing loss is not consistent with NIHL, then the evidentiary requirements are not met and work-related NIHL entitlement cannot be established.
In rare cases where the evidentiary requirements are met but a worker’s occupational noise exposure just meets the NET, it may be determined that the worker’s occupational noise exposure did not significantly contribute to the worker’s NIHL. Where a worker has just met the NET, has a hearing assessment conducted a considerable number of years after they have left the occupational noise exposure, and there are other non-work-related contributors to the hearing loss, the claim will be reviewed based on the individual facts and circumstances to determine entitlement.
Assessing the evidentiary requirements for initial entitlement
1. Determine whether hearing loss is present
Hearing loss is present when a worker has an average hearing level that is equal to or greater than 26.25 dB in each ear.
The average hearing level in each ear is calculated using the thresholds at the four key speech frequencies: 500 Hz, 1000 Hz, 2000 Hz, and 3000 Hz.
If the worker’s average hearing level is below 26.25 dB in either ear, the worker is not considered to have an occupational disease.
2. Determine whether the hearing loss is consistent with NIHL
Hearing loss is consistent with NIHL when the worker’s hearing assessment identifies permanent bilateral sensorineural or permanent bilateral mixed hearing loss. Where a sensorineural component is not established, this means that there is only conductive hearing loss. Conductive hearing loss results from damage to the outer or middle ear which is not compatible with NIHL.
To calculate the average hearing loss, both air and bone conduction values are reviewed. A large air-bone-gap with air conduction values that are 15 dB or greater than bone conduction values is indicative of either mixed or only conductive hearing loss.
For hearing loss that is sensorineural or mixed, both the air and bone conduction values for each of the frequencies are reviewed. Where there is both a value for air and bone for a particular frequency, the bone value associated with that frequency will be used to calculate the average hearing loss. If a particular frequency can only have an air value, then the air value will be used to calculate the average.
Asymmetrical hearing loss
NIHL often presents as symmetrical hearing loss (affecting both ears equally) but can also be asymmetrical. Asymmetrical hearing loss is loss that is greater in one ear than the other.
Asymmetry is consistent with NIHL when the difference in average hearing loss is 15 dB or less between ears. For example, an individual with an average hearing loss of 27 dB in the right ear and 42 dB in the left ear has a difference in average loss between ears of 15 dB. As each ear has an average loss greater than 26.25 dB, and the asymmetry does not exceed 15 dB, the difference is considered consistent with NIHL.
When the degree of asymmetry exceeds 15 dB, the decision-maker must be satisfied that the worker was exposed to occupational noise exposure that itself was asymmetrical (e.g., repeated noise exposure to sirens or engine noise on one side) to support that the asymmetry is consistent with NIHL.
Consistency of audiogram pattern with NIHL
The pattern of an audiogram may be relevant when determining whether the worker’s hearing loss is consistent with NIHL.
Where the audiogram pattern is consistent with NIHL (e.g., the classic “notch” or “dip”), it supports a finding that the worker’s hearing loss is due to noise exposure. Where the audiogram pattern is not consistent with NIHL, it does not necessarily support that the worker’s hearing loss is not due to noise exposure. However, it may be an indicator that further examination of the hearing loss may be required to consider if the loss is due to something other than noise. For example, an upward or reverse sloping audiogram may suggest an alternate cause of the hearing loss, such as Meniere’s Disease.
Audiogram patterns may require more scrutiny when,
- the hearing loss is asymmetrical, with a difference between ears of more than 15 dB,
- there is evidence suggesting an atypical audiogram pattern or a plausible non-noise-related cause of the hearing loss,
- there are multiple audiograms post exposure employment, or
- the worker’s occupational noise exposure does not meet or approach the NET.
3. Determine whether the NIHL is due to occupational noise exposure
Claims that meet or exceed the NET
Occupational exposure to noise is generally considered sufficient to have significantly contributed to the development of NIHL when it meets or exceeds the NET: a time-weighted average noise level of 90 dBA, measured over an 8-hour workday, for a cumulative duration of at least 5 years.
As occupational noise levels increase, NIHL may develop over a shorter duration of exposure. Conversely, lower levels of occupational noise may require a longer duration of exposure to produce the same effect. According to International Organization for Standardization (ISO) 1999 (2013) data, the following combination of noise level (dBA, 8-hour time-weighted average), and duration of exposure (in years), are considered equivalent to a time-weight average noise level of 90 dBA for 5 years:
- 84 dBA for 40 years
- 85 dBA for 28 years
- 86 dBA for 20 years
- 87 dBA for 14 years
- 88 dBA for 10 years
- 89 dBA for 7 years
- 91 dBA for 3.5 years
- 92 dBA for 2.5 years
- 93 dBA for 1.8 years
- 94 dBA for 1.25 years
The calculation for the worker’s occupational noise exposure is adjusted to account for variations in noise exposure, such as fluctuating exposure levels or changes in the durations of the noise exposure.
Claims that do not meet the NET
Where a worker’s occupational exposure to noise does not meet the NET, initial entitlement for NIHL may still be considered. The decision-maker considers the individual facts and circumstances of the claim, to determine if the evidence supports that the worker’s exposure to noise, in combination with other factors, significantly contributed to the development of their NIHL.
These relevant factors may include:
- A worker’s individual susceptibility to NIHL when supported with medical evidence.
- Occupational exposure to noise combined with occupational chemical exposures that could cause hearing loss.
- The nature of the exposure included continuous noise accompanied by intermittent, abrupt, or explosive sounds.
Asymmetrical noise exposure
In all circumstances, when the average hearing loss between ears exceeds 15 dB, the decision-maker must be satisfied that the occupational noise that the worker was exposed to was asymmetrical (e.g., repeated noise exposure to sirens or engine noise on one side) to produce the asymmetrical hearing loss demonstrated in the hearing assessment.
Employment noise exposure evidence
To determine whether a worker’s NIHL is work-related, decision-makers assess the relevance and weight of different types of evidence.
Employment noise exposure evidence that is reliable and reflective of the worker’s actual exposures are generally given greater weight which include:
- Personal noise exposure monitoring conducted with an external microphone and a professional, properly calibrated noise dosimeter that meets Canadian professional noise dosimeter standards for regulatory use. Its reliability may be reduced if the data is short-term or collected under atypical conditions.
- Workplace-specific noise surveys conducted by the employer or provincial government and reflect the worker’s actual duties, work area, and time period of employment.
General or industry-wide data such as provincial government reports on noise levels in similar industries or occupations or noise-level data from other reliable databases may also support conclusions about likely exposure, particularly when more specific evidence is unavailable.
HPD use
HPD use should not be factored into the assessment of whether a specific period(s) of occupational noise exposure with a particular employer has met the NET or an equivalent noise exposure, as HPDs do not alter the underlying noise hazard in the workplace.
HPD use, on its own, is not sufficient to determine that the NIHL is not work-related if the overall evidence supports the worker’s occupational exposure to noise met or exceeded the NET.
However, HPD use may strengthen a conclusion that the NIHL is not work-related when considered alongside other evidence suggesting that the employment was not a significant contributor to the hearing loss, such as,
- occupational noise exposure that was brief, intermittent, or limited in duration or level (lower than the NET), or
- non-occupational exposure to noise that could reasonably account for the hearing loss.
Exposure in non-covered employment
Occupational exposure to noise that occurs from non-covered employment is not work-related exposure. These exposure periods are excluded when determining whether a worker’s employment exposure meets the NET or was otherwise sufficient to have significantly contributed to the development of NIHL.
These periods include exposure that occurred:
- while the worker was self-employed and had not taken out optional insurance for coverage with the WSIB. Refer to 12-03-02, Optional Insurance, for more information.
- while the worker was employed by an employer who did not operate in a mandatorily covered industry and had not opted to acquire coverage by application with the WSIB. For more information, refer to 12-01-02, Employer by Application.
- outside of Ontario where the worker would not have continued to be covered under the WSIA for that out-of-province employment. Refer to 15-01-08, Out of Province, for additional information.
Entitlement to health care
When a worker’s NIHL claim is allowed, the worker is entitled to such health care as may be necessary, appropriate, and sufficient for the NIHL. This includes health care for tinnitus if accepted as a symptom of the work-related NIHL. For more information, refer to 17-01-02, Entitlement to Health Care, and 17-07-04, Hearing Devices.
Permanent impairment and NEL benefits
A worker with initial entitlement for NIHL has a permanent impairment and is entitled to a NEL benefit based on the degree of their work-related permanent impairment.
The degree of permanent impairment is determined using the prescribed rating schedule, the American Medical Association Guides to the Evaluation of Permanent Impairment, Third Edition (Revised) (AMA Guides). For more information, refer to 18-05-03, Determining the Degree of Permanent Impairment.
Hearing loss averages are expressed in whole numbers (not rounded) for permanent impairment calculations using the AMA Guides. Under the AMA Guides, the degree of permanent impairment for hearing loss averages of 26.25 dB in each ear is rated at 1%; whereas, when the average hearing loss in each ear exceeds 91.7 dB, this is considered a total hearing impairment with a maximum rating of 35%. For additional information on how the NEL benefit is calculated after the degree of work-related impairment is determined, refer to 18-05-04, Calculating NEL Benefits.
Exclusion of non-covered occupational exposure in determining permanent impairment
When determining the degree of work-related permanent impairment resulting from occupational exposure to noise, all exposure that occurred during covered employment is included. This encompasses both the exposure period(s) that is attributable to the employer who significantly contributed to the development of NIHL for initial entitlement to NIHL, and any other prior noise exposure periods where the worker had coverage under the WSIA. All non-covered exposure is not compensable and is removed from the permanent impairment determination.
To calculate the compensable portion of the impairment, the WSIB:
- determines the extent of the total permanent impairment in accordance with the AMA Guides (e.g., 12%)
- calculates the total duration of the worker’s noise exposure across all employment (e.g., 20 years)
- identifies the portion of that exposure that occurred in covered employment (e.g., 10 years)
- determines the percentage of covered employment exposure (e.g., 10 ÷ 20 = 50%)
- applies that covered employment percentage to the total permanent impairment (e.g., 12% x 50% = 6%)
The resulting NEL benefit is based on the compensable impairment of 6%, which reflects only the permanent impairment attributable to the occupational exposure to noise in covered employment.
Pre-existing conditions unrelated to non-covered occupational exposure in determining permanent impairment
For guidance on how to determine the degree of work-related permanent impairment resulting from noise exposure for those workers who also have a measurable pre-existing condition (unrelated to noise exposure) affecting the same body area, refer to 18-05-03, Determining the Degree of Permanent Impairment.
Further occupational noise exposure resulting in a significant deterioration
If a worker with an allowed NIHL claim experiences a significant deterioration in their NIHL hearing loss, additional NEL benefit entitlement is only assessed if the worker has further occupational exposure.
For clarity, if a worker does not remain in or return to occupational noise exposure in covered employment, any subsequent change in hearing loss is not considered work-related and is not eligible for additional NEL entitlement.
To consider any significant deterioration, the degree of permanent impairment to the worker’s hearing loss averages must increase by at least 10 dB in each ear from the prior level for the decision-maker to revisit the NEL benefit.
If the minimum change to the degree of permanent impairment is satisfied, the decision-maker then determines whether the worker’s work-related NIHL has deteriorated. The level and duration of the additional occupational noise exposure is examined to determine if it has sufficiently contributed to the change in hearing loss. The new hearing loss health care information is reviewed to assess frequency levels, characteristics of NIHL, and non-work-related factors.
Workers are encouraged to provide valid audiograms conducted while they are still employed in occupational noise exposure or as close to the date of cessation of occupational noise exposure. Generally, the greater the time between the last occupation noise exposure and the date the audiogram is conducted, the more difficult it may be to determine that the work-related NIHL has deteriorated.
Permanent impairment for NIHL-related tinnitus
Where a claim for NIHL has been allowed, an increase to the NEL benefit for permanent tinnitus (unilateral or bilateral) may be considered when,
- the tinnitus is not solely attributable to other causes and therefore is accepted as associated with the work-related NIHL, and
- there is dated and documented health care information that describes the extent of the ongoing tinnitus and demonstrates continuity for a minimum duration of two years, provided by an audiologist or another qualified, regulated health professional.
Earliest eligibility for NIHL-related tinnitus
If NIHL-related tinnitus was present before the date of accident, the earliest eligibility date on which an increase to the NEL benefit may be considered is two years after the date of accident, provided the tinnitus remains ongoing. However, if NIHL-related tinnitus was first present after the date of accident, the earliest eligibility date is two years from the documented onset of the symptom, provided the tinnitus remains ongoing.
Determining the degree of work-related permanent impairment for NIHL-related tinnitus
The degree of permanent impairment for NIHL-related tinnitus is rated at 2%. A NIHL-related tinnitus rating does not exceed 2% except for in rare cases where the ongoing tinnitus is supported with documentation provided by a specialist in otolaryngology outlining the history, the specific treatment(s) provided, and the extent of the symptom. The health care information on file is assessed to determine a possible increase to the 2% rating under the AMA Guides.
The permanent impairment ratings for NIHL hearing loss and NIHL-related tinnitus are combined using the AMA Guides Combined Values Chart to calculate the NEL benefit.
Date of accident
For NIHL claims, the date of accident is the earlier of,
- the date of the audiogram that first confirms the presence of a hearing loss impairment that coincides with sufficient occupational exposure, or
- the date a loss of earnings first occurs due to a hearing loss impairment that coincides with sufficient occupational exposure.
Where the date of accident recorded at the time of claim registration differs from the aforementioned dates, it may need to be adjusted to reflect the appropriate date at the time of adjudication.
Application date
This policy applies to all decisions, with an exception as stipulated for NIHL-related tinnitus, made on or after October 7, 2026, for all accidents occurring on or after January 2, 1990.
This policy applies to all decisions made for new requests for NIHL-related tinnitus entitlement claimed on or after October 7, 2026, for all accidents occurring on or after January 2, 1990. For NIHL-related tinnitus entitlement requests claimed prior to October 7, 2026, refer to 16-01-08, Tinnitus On/After January 2, 1990, up to October 6, 2026.
Document history
This document replaces 16-01-04 dated July 20, 2023.
This document was previously published as:
16-01-04 dated July 18, 2008
16-01-04 dated October 12, 2004
04-03-10 dated July 23, 1993.
References
Legislative authority
Workplace Safety and Insurance Act, 1997
Sections 2(1),15(1),15(2),33,46,47,106,119(1)
Ontario Regulation 175/98
Section 18
Workers' Compensation Act, Revised Statutes of Ontario, 1990
Section 1(1),42,50,73(1),134
Revised Regulations of Ontario, 1990, Regulation 1102
Section 15
Approval
Approved by the President and CEO on September 2, 2026.