1. On 31 March 2025 the appellant, T.N.T. Plumbing & Drainage Pty Ltd, lodged an Application to Appeal Against the Decision of a Medical Assessor. The medical dispute was assessed by Dr Henley Harrison, a Medical Assessor, who issued a Medical Assessment Certificate (MAC) on 17 March 2025.
2. The appellant relies on the following grounds of appeal under s 327(3) of the Workplace Injury Management and Workers Compensation Act 1998 (the 1998 Act):
   • the assessment was made on the basis of incorrect criteria, and
   • the MAC contains a demonstrable error.
3. The delegate is satisfied that, on the face of the application, at least one ground of appeal has been made out. The Appeal Panel has conducted a review of the original medical assessment but limited to the ground(s) of appeal on which the appeal is made.
4. Rule 128 of the Personal Injury Commission Rules 2021 (the PIC Rules) and Procedural Direction PIC7 - Appeals, reviews, reconsiderations and correction of obvious errors in medical disputes set out the practice and procedure in relation to the medical appeal process under s 328 of the 1998 Act. An Appeal Panel determines its own procedures in accordance with r 128(1) of the PIC Rules.
5. The assessment of permanent impairment is conducted in accordance with the SIRA NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment, 4th ed

1 March 2021 (the Guidelines) and the American Medical Association Guides to the Evaluation of Permanent Impairment, 5th ed (AMA 5).

1. The respondent worker, Jeffrey Auburn Robinson, has provided a statement dated 21 January 2025 which sets out a history of his exposure to noise in the course of his working life, which is summarised as follows:
   • working as a mechanical fitter with various employers from 1983 to 1997;
   • working as a labourer with Pipeline Service Australia from 1997 to 2001;
   • being self-employed as a mechanical fitter from 2001 to 2012;
   • working as a truck driver and trades assistant with Pacific Rail Engineering from 2012 to October 2013;
   • being self-employed as a gardener, truck driver and excavator operator from 2013 to 2017;
   • working as a trades assistant with Arden Architectural Stairs from February 2017 to March 2019;
   • working as a trades assistant with Expanda Van Homes Pty Ltd for a month in March 2019, and
   • working as a fitter and plant operator with the appellant from 8 April 2019 to 30 October 2019.
2. The respondent states that he has been self-employed as a mechanical fitter since October 2019.
3. The respondent states he was exposed to noise for the whole of a working week, being eight hours per day for five days per week, when he was both employed and self-employed.
4. The respondent states that he has suffered with hearing problems for over seven years, and that his hearing has slowly became worse over the years.
5. The respondent made a claim for 11% whole person impairment (WPI) as a result of hearing loss sustained in the course of his employment, with a deemed date of injury of 30 October 2019, being the last date on which he was employed in an employment to the nature of which the injury was due. That claim is based upon an assessment made by Dr Fagan in reports dated 19 February 2024 and 6 March 2024.
6. Dr Fagan set out a detailed work history, including the periods between 2001 and 2012, and between 2013 and 2017, when the respondent was self-employed as a mechanical fitter and exposed to excessive noise. Dr Fagan records that the respondent was exposed to noise for at least eight hours per day for five days per week when he was both employed and self-employed.
7. Dr Fagan opined that the respondent's hearing loss from 1000Hz to 4000Hz was due to noise exposure having regard to the long exposure period and the audiogram configuration which was performed, and that there was no other explanation for this loss besides noise exposure. Dr Fagan did not make any deduction for any hearing loss during the periods when the respondent was self-employed.
8. The respondent obtained a report from Dr Williams dated 18 July 2024 which assessed the respondent as having 5% WPI. Dr Williams did not make any deduction for any hearing loss during the periods when the respondent was self-employed.
9. Consent Orders were entered into on 5 March 2025 in regard to the referral of this dispute to a Medical Assessor for the assessment of WPI which included the following:

"2. The parties jointly request the Medical Assessor specifically consider any section 323 deduction pursuant to the 1998 Act relating to the applicant's self-employment between 2013 and 2017 and between 2012 to October 2013 (paragraphs 9 and 11) of the applicant's statement found at folio 2 and 3 of the ARD."

1. The submissions from the appellant refer to those Consent Orders being amended by deleting reference to paragraphs 8 and 10 of the respondent's statement, and instead referring to paragraphs 9 and 11 of that statement, which relate to the periods when the appellant was self-employed.
2. A MAC was issued by Dr Henley C Harrison on 17 March 2025 wherein the respondent was assessed as having 13% WPI, with a one-tenth deduction made pursuant to s 323 of the 1998 Act for the periods of self-employment which have contributed to the respondent's exposure to noise. The WPI as a result of binaural hearing loss was therefore certified to be 12%.

1. The Appeal Panel conducted a preliminary review of the original medical assessment in the absence of the parties and in accordance with the Procedural Direction PIC7.
2. As a result of that preliminary review, the Appeal Panel determined that it was not necessary for the worker to undergo a further medical examination because even though the Appeal Panel found there was a demonstrable error in the MAC, there was sufficient material available to make a determination.

1. The Appeal Panel has before it all the documents that were sent to the Medical Assessor for the original medical assessment and has taken them into account in making this determination.

1. The Medical Assessor set out the respondent's work history that is mostly consistent with the details set out in the applicant's statement and in paragraph 6 of this decision.
2. The Medical Assessor records that the respondent was self-employed as a gardener between 2013 and 2017. The Medical Assessor writes:

"In view of the consent orders I questioned him carefully about this which caused him some confusion. He said that about 50% of the time was spent using a motorised lawnmower which made noise such that in its presence he would have to raise his voice or shout for someone with normal hearing to understand him at a distance of 1 m and that there was other work site noise as described in the statement. He said that he thought that overall the noise exposure was similar to that with Expanda. Hearing protection was not worn. Overall I gained the impression of damaging hearing and that it had probably done so."

1. The Medical Assessor records that the respondent has been having difficulties with hearing for longer than the seven years which the respondent refers to in his statement dated 21 January 2025.
2. The Medical Assessor makes an assessment of 31.7% binaural hearing loss, and then deducts 6.7% for hearing loss not related to work and 0.4% for presbycusis, and then adds 1% for severe tinnitus. The adjusted total for binaural hearing loss is then 25.6%, which results in 13% WPI. A one-tenth deduction is then made pursuant to s 323 of the 1998 Act for the periods of self-employment which have contributed to the respondent's exposure to noise.
3. The explanation provided by the Medical Assessor for the one-tenth deduction of WPI is set out as follows:

"However there have been 2 periods of self-employment as indicated above and a section 323 deduction for this is appropriate as suggested in the consent orders. It would be difficult or costly to determine the exact extent to which these periods of self-employment have contributed to the whole noise exposure so I have made a section 323 (2) deduction of 1/10 to take this into account. 1/10 of 13% is 1.3% which, rounded to the closest whole number is 1%. Deducting 1% WPI from 13% WPI gives 12% WPI requiring compensation."

1. Both parties made written submissions. They are not repeated in full, but have been considered by the Appeal Panel.
2. The appellant submits that the MAC contains the following demonstrable errors:

(a) failing to provide any adequate reasons for concluding that it would be "difficult or costly" to perform the statutory task required by s 323 (1) of the 1998 Act;

(b) wrongly refusing to apply s 323 (1) of the 1998 Act on the ground that the required statutory task cannot be carried out unless it is "exact";

(c) failing to consider whether the one-tenth deduction was "at odds with the available evidence" within the meaning of s 323 (2) of the 1998 Act, and

(d) failing to determine the extent of the deduction pursuant to s 323 of the 1998 Act on the basis of the available evidence, or in the alternative, making an insufficient deduction.

1. The appellant submits that an examination of the respondent's work history reveals that he was self employed for nearly 40% of the time that he was exposed to noise while undertaking work, and that the deductible proportion should therefore be in the order of 40%.
2. The appellant submits that the Medical Assessor did not engage with the material presented to him. The appellant submits that there was no additional cost in carrying out the required assessment of the appropriate deduction because of the material made available to him.
3. The respondent submits that he was exposed to similar or greater noise in his later periods of employment with Arden Architectural Stairs, Expanda Van Homes Pty Ltd and the appellant than when he was self-employed. He submits that there is no evidence to evaluate the intensity and magnitude of the noise exposure with those employers. However, he submits that his hearing problems did not develop until over seven years prior to his statement dated 21 January 2025.
4. The respondent submits that there are no clinical records or medicolegal opinions to assist the Medical Assessor in making a deduction pursuant to s 323 (1) of the 1998 Act.
5. The respondent submits that the Medical Assessor was not obliged to adopt what was referred to in Cuskelly v New England Milk Industries Pty Ltd [2020] NSWWCCMA 2 (Cuskelly) at [43] as a 'linear' assessment in the application of s 323 (1) because the nature of his exposure to noise differed significantly between various periods of employment.

1. The procedures on appeal are contained in s 328 of the 1998 Act. The appeal is to be by way of review of the original medical assessment but the review is limited to the grounds of appeal on which the appeal is made.
2. In Campbelltown City Council v Vegan [2006] NSWCA 284 the Court of Appeal held that the Appeal Panel is obliged to give reasons. Where there are disputes of fact it may be necessary to refer to evidence or other material on which findings are based, but the extent to which this is necessary will vary from case to case. Where more than one conclusion is open, it will be necessary to explain why one conclusion is preferred. On the other hand, the reasons need not be extensive or provide a detailed explanation of the criteria applied by the medical professionals in reaching a professional judgement.
3. The Appeal Panel considers it is incumbent upon the Medical Assessor to provide adequate reasons as to why there should only a one-tenth deduction from the assessment of WPI due to the periods when the respondent was self-employed. It is not sufficient for the Medical Assessor to merely state that it would be difficult or costly to determine the deduction for the hearing loss which pre-existed as a result of the respondent being self-employed, without some explanation for reaching this conclusion.
4. The need for such an explanation was emphasised by Basten J in Secretary, Department of Communities and Justice v Virtue [2024] NSWSC 1380 (Virtue) at [33]:

"...the medical assessor in fact identified previous injuries and pre-existing conditions or abnormalities with respect to the left knee, but the reason he gave for applying the default deduction was that '[t]he extent of the deduction is difficult or costly to determine'. That was a somewhat glib recitation of the opening words of s 323(2). It would not have been 'costly' because no-one was suggesting any further steps be taken; the assessment can have been no more difficult than was the assessment of the rest of the medical evidence, including that relating to the right knee. That statement did not constitute an adequate reason for failing to make the appropriate assessment on the evidence available to the assessor, pursuant to s 323(1). Nor did it address the qualification to the application of s 323(2), namely that the default position not be at odds with the evidence. On either approach, the evidence had to be addressed and was not."

1. The Appeal Panel therefore finds that the MAC contains a demonstrable error by the failure to provide an explanation for the one-tenth deduction from the assessment of WPI. This Panel now needs to determine the application of s 323 of the 1998 Act having regard to the circumstances of this dispute.
2. Section 323 of the 1998 Act relevantly provides:

"(1) In assessing the degree of permanent impairment resulting from an injury, there is to be a deduction for any proportion of the impairment that is due to any previous injury (whether or not it is an injury for which compensation has been paid or is payable under Division 4 of Part 3 of the 1987 Act) or that is due to any pre-existing condition or abnormality.

(2) If the extent of a deduction under this section (or a part of it) will be difficult or costly to determine (because, for example, of the absence of medical evidence), it is to be assumed (for the purpose of avoiding disputation) that the deduction (or the relevant part of it) is 10% of the impairment, unless this assumption is at odds with the available evidence.

(3) The reference in subsection (2) to medical evidence is a reference to medical evidence accepted or preferred by the medical assessor in connection with the medical assessment of the matter."

1. The Appeal Panel notes there is no challenge by either party to the actual assessment of hearing loss made by the Medical Assessor.
2. The Appeal Panel also considers that the Medical Assessor has obtained a comprehensive history of the respondent's employment and self-employment throughout his working life, and he has done his best to record details of noise exposure during those periods of employment and self-employment.
3. Both parties in their submissions referred to Cuskelly v New England Milk Industries Pty Ltd [2020] NSWCCMA 2 (Cuskelly), which identified two different methods of assessing WPI for hearing loss where there have been periods when a worker has been exposed to noise in employment outside of New South Wales. Those methods are the 'linear' or 'temporal' method and the use of epidemiological data. Those two methods, and the limitations using wither of those, were explained by the Appeal Panel in Cuskelly at [43]-[44]:

"The medical members of the Panel are of the view that, in a difficult case such as this, there are only two ways of assessing hearing loss. They are the years of exposure (or in the Panel's view, best described as the 'linear' or 'temporal') method, or by using the epidemiological data (ISO 1999) used by Dr Fernandes. The Panel notes that the BHL assessed by Dr Fernandes is similar to that assessed by the AMS using the linear or temporal method.

The Panel notes that both methods of assessment have limitations. However, in this regard it agrees with the initial preference expressed by the AMS, that in this case the linear method of assessment is appropriate. This is because although there is greater industrial deafness at the higher tones during the early years of exposure (in dBHL terms), but this tends to linearity (in BHI terms) as the lesion expands through time. This is because the cochlear noise lesion spreads temporally to progressively lower frequencies to which the NAL Table assigns higher values. The Panel also notes the history that Mr Cuskelly provided to the AMS that exposure to noise throughout his working life was relatively stable. This is supportive of the linear view. The epidemiological view (in ISO 1999) of this kind of apportionment is weakened by its never having been definitively canvassed in the published medical literature and because it is not an individual assessment being rather a central measure (an average) with limited account of actual real dispersion about a mean."

1. However, it is important to emphasise that Cuskelly did not involve the application of s 323 of the 1998 Act because the Approved Medical Specialist and Appeal Panel in that dispute were required to determine the hearing loss which was attributable to a lengthy period of employment outside of New South Wales after the worker had been employed in noisy employment in New South Wales, whereas this dispute involves the consideration of hearing loss which was sustained prior to the respondent's employment with the appellant.
2. The Appeal Panel considers that caution needs to be exercised in utilising the 'linear method' to determine the s 323 component in a claim for WPI. The 'linear method' is only a rough guide which can be utilised in certain circumstances to assist in a determination of that part of a hearing loss which is attributable to employment which does not occur in New South Wales.
3. In this dispute there are factors which militate against the use of the 'linear method'. Firstly, it is not certain at all as to whether the respondent's exposure to noise was uniform throughout his working life, being both when he was employed or self-employed. The respondent states that he was exposed to noise from truck engines, excavators and general worksite noise for 40 hours per week while was self-employed as a gardener, truck driver and excavator operator between 2013 and 2017.
4. However, the Medical Assessor records from the respondent that about 50% of his time was spent using a motorised lawnmower when he was self-employed as a gardener, and that this exposure to noise was similar to his exposure while employed with Expanda Homes for about two months in 2019. The Medical Assessor states that he questioned the respondent very carefully in regard to this in view of the terms of the Consent Orders.
5. The Appeal Panel would therefore not be confident in using the 'linear method' having regard to these details obtained by the Medical Assessor.
6. Secondly, although the respondent provides some details of his exposure to noise during his first period of self-employment between 2001 and 2012, that is some considerable time in the past, and there is little means of obtaining a more accurate understanding of the effect that the level of noise which the respondent was exposed to during this period of time had upon his hearing.
7. Furthermore, the respondent states in January 2025, and this is confirmed in the MAC, that he began to have difficulties with hearing over seven years ago, which is some 10 years after his first period of employment. There is therefore no medical evidence which is likely to assist in determining any likely hearing loss from exposure to noise in that first period of self-employment.
8. The Appeal Panel therefore concludes that it is difficult and costly based on the available evidence to make any deduction other than the one-tenth allowed for by s 323 (2) of the 1998 Act, and that such a deduction is not at odds with that evidence which has been made available in this dispute.
9. The Appeal Panel confirms that the MAC contains a demonstrable error but has come to the same determination of WPI as the Medical Assessor. There is therefore no utility in revoking the MAC. The assessment of WPI in the MAC issued on 17 March 2025 is confirmed.