Statement of Principles concerning hyperacusis (Reasonable Hypothesis) (No. 27 of 2021)

The central concept is the “reasonable hypothesis” as used in the VEA and MRCA. This SOP does not define the term but instead specifies the minimum factors that will satisfy it for hyperacusis. The Authority has determined, per section 7, that there is sound medical-scientific evidence that hyperacusis and death from hyperacusis can be related to relevant service rendered by veterans, members of Peacekeeping Forces, or members of the Forces under the VEA, or members under the MRCA.

Hyperacusis as defined requires three elements: (a) a disorder of sound tolerance with increased sensitivity or decreased tolerance to everyday sounds that would not disturb most individuals; (b) significant distress and impairment in social, occupational, recreational and other day-to-day activities; and (c) persistence for at least three months. This distinguishes hyperacusis from transient noise sensitivity or phonophobia. The definition expressly includes sounds generated within the body as potential triggers.

“Acoustic shock” is defined in the dictionary as the development of acoustic shock symptoms within 30 days of exposure to a brief, sudden, unexpected, loud sound. Acoustic shock symptoms are in turn defined by reference to the Work Health and Safety (Managing Noise and Preventing Hearing Loss at Work) Code of Practice 2015, and include a feeling of fullness in the ear, burning sensations or sharp pain, dizziness, hypervigilance, numbness/tingling/soreness down the side of face/neck/shoulder, and tinnitus. This is a key factor for both onset and worsening (factors 4 and 22).

The noise exposure metrics are carefully defined. “dB(A)” means sound pressure level in decibels measured with a type A electronic filter. “dB(C)” means decibels measured with a type C electronic filter, used for peak or impact sound pressure levels. “Time-weighted average (TWA) with a 3-dB exchange rate” adopts the National Institute of Occupational Safety and Health 1998 Guidelines formula, with a table of exposure levels and durations. The 3-dB exchange rate means that every 3 dB increase halves the permissible exposure duration, which is a more protective standard than the 5-dB exchange rate used in some other noise regulations.

The “specified list of inner ear disorders” includes lateral semicircular canal dysplasia, perilymphatic fistula, stapes hypermobility, and superior semicircular canal dehiscence. The “specified list of viral or bacterial infections” includes neurosyphilis, Lyme disease, Orientia tsutsugamushi infection (scrub typhus), and Rickettsia prowazekii infection. These are narrow categories.

“Long-term benzodiazepine use” means taking a benzodiazepine daily for at least three months. This triggers a withdrawal window of seven days for factor 18 (onset) and factor 36 (worsening). The instrument thus recognises medication-related causation but sets a high threshold of daily use for a substantial period.

“Relevant service” is defined in the dictionary to include operational, peacekeeping, hazardous, and British nuclear test defence service under the VEA, and warlike and non-warlike service under the MRCA. This determines the population eligible to rely on the SOP.

The SOP directly affects veterans and members who have rendered “relevant service” as defined: operational service under the VEA, peacekeeping service, hazardous service, British nuclear test defence service, and warlike or non-warlike service under the MRCA. This includes members of the Australian Defence Force, Peacekeeping Forces, and Forces under the VEA. Claimants seeking compensation for hyperacusis or death from hyperacusis must satisfy the SOP to raise a reasonable hypothesis connecting the condition to service.

Indirectly, the SOP affects the Department of Veterans’ Affairs decision-makers (delegates under the VEA and MRCA), the Veterans’ Review Board, the Administrative Appeals Tribunal, and ultimately federal courts reviewing decisions. It also affects medical professionals who provide reports and opinions in support of claims. They must be familiar with the specific definitions and factor lists to assess whether a claimant meets the minimum threshold. The SOP constrains the scope of expert evidence: only the listed factors can be used to establish a reasonable hypothesis, though a medical practitioner may still opine on whether a factor exists.

Legal practitioners and advocates representing veterans must use the SOP as a checklist. The instrument creates a predictable framework but also places a burden on claimants to produce evidence tying a specific factor to their service history. For example, to rely on the noise exposure factors, a claimant must provide evidence of peak or cumulative noise levels during service that meet the thresholds. This may require historical records, witness statements, or job exposure matrices.

The SOP also affects the dependents of veterans who die from hyperacusis or from a terminal event contributed to by hyperacusis. The definition of death from hyperacusis includes cases where hyperacusis contributed to pneumonia, respiratory failure, cardiac arrest, circulatory failure, or cessation of brain function. This expands the class of potential claimants beyond those who die directly from the condition.

Clinicians treating hyperacusis may need to provide detailed documentation regarding the timing of clinical onset or worsening relative to service exposures. The three-month persistence requirement means that transient symptoms do not qualify, which may affect the number of successful claims. The requirement for significant distress and impairment in day-to-day activities adds a functional threshold that must be clinically assessed.

The SOP does not impose duties in the ordinary sense; it is an evidentiary instrument that establishes the minimum factors for a reasonable hypothesis. The key right it confers on claimants is the ability to rely on an exhaustive list of known causal factors to satisfy the evidentiary stage of a compensation claim. If a claimant can show that at least one factor in section 8 exists and is related to their relevant service, then the decision-maker must treat the reasonable hypothesis as having been raised. This is a significant right because it removes the need for the claimant to prove causation on the balance of probabilities at the primary stage; the burden shifts to the decision-maker to disprove the hypothesis or to find that the factor is not related to service.

The duty lies with the decision-maker to correctly apply the SOP. They must determine whether the claimant’s hyperacusis meets the definition in subsection 6(2), including the three-month persistence and functional impairment criteria. They must then assess whether any factor in section 8 exists in the claimant’s circumstances and whether that factor is related to the relevant service. For factors 1 and 19 (peak noise), the decision-maker must be satisfied that the peak sound pressure level at the tympanic membrane was at least 140 dB(C). For factors 2 and 20 (cumulative noise), they must calculate or accept evidence that the noise exposure was at least 85 dB(A) as an 8-hour TWA with a 3-dB exchange rate for a cumulative period of at least six months. The instrument provides no discretion to consider other factors not listed; once a factor is satisfied and related to service, the hypothesis is raised.

The claimant also has a duty to provide sufficient evidence. The SOP itself does not mandate evidence formats, but as a practical matter, the claimant must produce service records, medical reports, and exposure data to demonstrate the factor. For example, to rely on the sensorineural hearing loss factor (3 and 21), audiometric evidence at the time of clinical onset or worsening is needed. For acoustic shock (4 and 22), evidence of a sudden loud sound event within 30 days before symptom onset is required.

Factor 37 (inability to obtain appropriate clinical management for hyperacusis) is unique. It applies only to worsening, per section 9(2), and requires that the inability be related to service. This could cover situations where a veteran’s service location or post-service circumstances prevented access to treatment. The claimant has a right to argue that the inability was caused or contributed to by service, but the evidential burden is likely high: they would need to show that appropriate clinical management was available but not obtainable due to service-related factors such as remote posting or service-connected financial constraints.

The SOP itself does not create any civil or criminal penalties. It is a legislative instrument that sets evidentiary standards for compensation claims. However, the underlying legislation (VEA and MRCA) contains offences for making false or misleading statements in connection with claims. A claimant who fabricates evidence to satisfy a factor under this SOP could face penalties under the Criminal Code or specific provisions of those Acts. Similarly, a medical practitioner who provides a report that falsely asserts the existence of a factor could be liable for professional misconduct or fraud.

The enforcement mechanism is indirect: if a decision-maker incorrectly applies the SOP, the claimant may appeal to the Veterans’ Review Board and then to the Administrative Appeals Tribunal or federal courts. An incorrect application that favours the claimant could later be recovered by the Department if fraud is discovered. There is no penalty for the decision-maker who misapplies the SOP in good faith, though systemic errors could lead to internal review or policy changes.

The Repatriation Medical Authority itself is not an enforcement body; it determines the SOP based on medical-scientific evidence. Its determination is not reviewable on the merits, though a court could invalidate the SOP if it exceeded the authority under the VEA or was made without proper process.

The SOP does not include any compliance obligations on employers, manufacturers, or third parties. It is purely a claims-assessment tool. The practical “penalty” for a claimant who cannot meet a factor is that they will not be able to raise a reasonable hypothesis, and their claim will fail at the first stage. This could be seen as a barrier, but the list of factors is broad.

Note that the reference to the Work Health and Safety Code of Practice in the definition of “acoustic shock symptoms” imports a regulatory standard, but that Code does not bind decision-makers under the VEA or MRCA; it is merely used as a definitional reference. There is no penalty for not adhering to the Code in the service context, though breaches of workplace health and safety laws could separately arise.

The SOP operates under the VEA and MRCA. Section 4 states it applies to claims to which section 120A of the VEA or section 338 of the MRCA applies. Those provisions set out the standard of proof for claims relating to injury, disease or death: for operational service, the standard is reasonable hypothesis unless disproved beyond reasonable doubt; for other service, the standard is balance of probabilities. The SOP fills in the content of “reasonable hypothesis” for hyperacusis.

Section 10 of the SOP provides for interaction with other Statements of Principles: if a factor in section 8 refers to an injury or disease in respect of which another SOP has been determined under subsection 196B(2) of the VEA, then the factors in that other SOP apply as in force from time to time. This is significant. For example, factor 5 (otitic barotrauma) might be defined by reference to another SOP; factor 10 (specified inner ear disorders) and factor 13 (specified infections) may themselves be the subject of separate SOPs. The decision-maker must check whether the injury or disease that is a factor under this hyperacusis SOP has its own SOP, and if so, must apply that SOP to determine whether the factor exists. This creates a layered analysis: first, decide if the person has the factor injury (e.g., Meniere’s disease), using any applicable SOP for Meniere’s; then, decide if that factor is related to service; then, decide if the existence of that factor raises a reasonable hypothesis for hyperacusis.

The SOP does not interact directly with state or territory workers’ compensation laws, as it is specific to federal military compensation. However, the definitional borrowing from the Work Health and Safety Code of Practice (for acoustic shock symptoms) creates a link to national model work health and safety standards, but the Code is not binding in the VEA context. It merely provides a list of symptoms.

The noise exposure metrics reference the National Institute of Occupational Safety and Health 1998 Guidelines. Those are not Australian standards, but the SOP adopts them as the measure. This may cause confusion if other Australian noise regulations (e.g., under state WHS laws) use different exchange rates or measurement methods. Claimants with civilian noise exposure history cannot rely solely on those standards; the SOP requires the noise exposure to be related to relevant service, and the measurement must be in accordance with the NIOSH formula.

The instrument defines relevant service by reference to the VEA and MRCA, which themselves interact with other compensation schemes (e.g., the Safety, Rehabilitation and Compensation Act 1988 for Commonwealth employees outside the military). A person who has both military and civilian service can only use the hyperacusis SOP for the military component.

The instrument does not repeal or amend any previous SOP on hyperacusis, but as a later instrument it effectively supersedes any prior version. There is no sunset clause or review date mentioned.

The source provides the instrument as made on 24 December 2020 and commencing on 25 January 2021. No amendment history is included in the source text. The instrument bears the number No. 27 of 2021, indicating it is the 27th SOP made in that year. It was made under subsection 196B(2) of the VEA by the Repatriation Medical Authority. The Authority’s seal was affixed on 24 December 2020. There is no mention of any prior SOP for hyperacusis that this one replaces or amends. Practitioners should verify with the Federal Register of Legislation whether any subsequent amendments have been made after the date of the source. It is common for SOPs to be revoked and replaced by new versions when new medical evidence emerges, but this instrument appears to be the current one as at the effective date. The schedule includes a note that the table of noise exposure levels is sourced from NIOSH 1998, which may be updated in future versions. The dictionary definitions are exhaustive as provided.

The source does not mention any litigation, court decisions, or tribunal rulings. As a legislative instrument, it cannot be the subject of direct challenge on its merits, though its validity could be challenged on jurisdictional grounds (e.g., whether the Authority had power under s196B(2) or whether the factors are supported by sound medical-scientific evidence). No such challenges are referenced.

At the time of writing the deep dive, no specific cases interpreting this particular SOP are available from the source. However, it is likely that the Administrative Appeals Tribunal and the Federal Court have considered previous versions of hyperacusis SOPs, particularly on issues such as the definition of hyperacusis, the noise exposure thresholds, and the application of the acoustic shock factor. The current SOP might have been revised in response to previous litigation. For example, the inclusion of the three-month persistence requirement and the requirement for significant distress and impairment may have been added to clarify the disorder and exclude transient sensitivity. The specific list of inner ear disorders and infections may have been narrowed from earlier versions.

The decision-maker and advocates should be aware that even with a valid SOP, the determination of whether a factor exists on the facts is a question of fact for the tribunal. The SOP does not guarantee success; it only provides the gateway to the reasonable hypothesis stage. Litigation may arise over the interpretation of terms such as “peak sound pressure level at the tympanic membrane” and the calculation of the time-weighted average. The reference to the NIOSH guidelines may be litigated if a party argues a different exchange rate should be used.

No class actions or representative proceedings are known from the source material.

Several aspects of the SOP may trap unwary practitioners. First, the definition of hyperacusis in subsection 6(2) requires that the disorder “causes significant distress and impairment in social, occupational, recreational, and other day-to-day activities” and “must have persisted for at least three months.” This is a higher threshold than many clinicians might use when diagnosing hyperacusis. A person who is merely annoyed by loud sounds or who has a mild sensitivity that does not significantly impair daily life will not meet the definition, even if they have a plausible service-related cause. The three-month persistence also means that acute or episodic sensitivity does not qualify unless it lasts continuously for at least three months.

Second, factor 37 (inability to obtain appropriate clinical management for hyperacusis) appears at first glance to be a catch-all that could apply in many cases. However, it applies only to clinical worsening, not to onset, per section 9(2). Moreover, the inability must be related to service. This means the claimant must show that they could not obtain appropriate management because of a service-related factor - for example, because the condition was not diagnosed due to inadequate military medical screening, or because they were posted to a location without audiology services. Simple difficulty in accessing treatment due to cost or wait times in the general community would not be sufficient unless the service caused or exacerbated that difficulty.

Third, the noise exposure factors require specific thresholds. For peak exposure, it must be at least 140 dB(C) at the tympanic membrane. Many sources of impulse noise in a military environment (e.g., rifle fire, explosions) produce peak levels well above this, but the measurement must be at the tympanic membrane, which may be lower than the ambient peak level if hearing protection was used. The SOP does not specify how to adjust for hearing protection. For cumulative exposure, the 85 dB(A) TWA with a 3-dB exchange rate for at least six months is a stringent standard. The 3-dB exchange rate is more conservative than the 5-dB exchange rate used in some civilian regulations, meaning it is easier to exceed the permissible cumulative dose. However, the requirement that the exposure be “for a cumulative period of at least six months” means that sporadic high-level exposure over a shorter period will not suffice.

Fourth, the definition of “acoustic shock” requires development of symptoms within 30 days of exposure to a brief, sudden, unexpected, loud sound. The symptoms are listed by reference to a Code of Practice. Notably, the symptom list includes hypervigilance and tinnitus, which could themselves be part of the hyperacusis presentation. This creates a risk of circular reasoning: the acoustic shock factor may rely on hyperacusis symptoms as part of the definition, but the SOP already defines hyperacusis. Practitioners must be careful to distinguish between the condition and the factor.

Fifth, factor 18 (benzodiazepine withdrawal) applies only to long-term use (daily for at least three months) and within seven days before onset. This is a narrow window. Many veterans may have used benzodiazepines intermittently, which would not qualify. Also, withdrawal from other medications is not covered.

Sixth, the instrument defines “relevant service” for the purpose of the SOP, but the claim may involve service that does not fall within that definition (e.g., peacetime service that is not operational or warlike). The factor must relate to the relevant service as defined; if the factor arises from non-relevant service, it cannot be used.

Seventh, the table for time-weighted average uses fractions of hours, minutes and seconds. The calculation formulae are algebraic; error in applying the formula could lead to incorrect conclusions. The source notes that the table is from NIOSH 1998, which may not be current but is the reference adopted.

For decision-makers (DVA delegates, tribunal members), compliance means applying the SOP strictly according to its terms. The steps are: (1) Determine if the claimant has hyperacusis as defined - ensure it has persisted for at least three months and causes significant distress and impairment. Obtain a medical report that addresses these criteria. (2) Identify the clinical onset and any clinical worsening. (3) Examine each factor in section 8 to see if any applies based on the evidence. For each potential factor, require proof: medical records, service records, exposure logs, audiological reports. (4) If a factor exists, determine whether it is related to the claimant’s relevant service. For factors 1-18 (onset), the relationship must be direct; for factors 19-37 (worsening), they apply only where hyperacusis existed before or during service but did not arise out of service, and the factor must be related to service. (5) If a factor refers to another injury or disease (e.g., Meniere’s), check if that condition has its own SOP and apply that SOP to determine if the factor is established. (6) If at least one factor is related to service, the reasonable hypothesis is raised; proceed to the next stage under VEA s120A or MRCA s338.

For claimants and advocates, compliance means assembling evidence to match a factor. Noise exposure factors require service records showing noise levels or job duties with known noise exposure. For the 140 dB(C) peak factor, obtain corroboration of an impulse noise event and, if possible, noise measurements. For the 85 dB(A) TWA factor, obtain cumulative noise exposure data or a job exposure matrix showing at least six months of exposure. For sensorineural hearing loss, provide a recent audiogram and one from around the time of hyperacusis onset. For acoustic shock, document the event and symptom onset within 30 days. For medical factors (e.g., Meniere’s, multiple sclerosis), obtain specialist diagnoses and ensure they are present at the time of onset or worsening.

A common compliance failure is not addressing the three-month persistence and functional impairment elements. The medical report should explicitly state that the symptoms have been present for at least three consecutive months and cause significant distress or impairment in daily life. The report should also specify the date of clinical onset and any dates of clinical worsening.

For factor 37, the claimant must demonstrate that appropriate clinical management (e.g., sound therapy, cognitive behavioural therapy, hearing protection counselling) was not obtainable, and that this inability relates to service. For example, a veteran discharged to a rural area without audiology services where the Department of Veterans’ Affairs did not fund travel could argue that the inability to obtain management is service-related because the location or funding constraints are connected to service. The claim should document attempts to access treatment and reasons for failure.

All claims should include a clear mapping of the evidence to the specific factor number and the wording of the factor. Avoid reliance on factors not listed. The SOP is exhaustive; creative arguments that hyperacusis was caused by factors outside the list will not raise a reasonable hypothesis under this instrument. However, the claimant could argue that a factor in the list is present even if the mechanism is not fully understood.

Finally, maintain awareness that the SOP may be amended or replaced. Check the Federal Register of Legislation for the latest version before finalising any claim or decision.