Wilson v Shoalbus Pty Ltd
[2024] NSWPICMP 462
•17 July 2024
| DETERMINATION OF APPEAL PANEL | |
| CITATION: | Wilson v Shoalbus Pty Ltd [2024] NSWPICMP 462 |
| APPELLANT: | David Wilson |
| RESPONDENT: | Shoalbus Pty Ltd |
| APPEAL PANEL | |
| MEMBER: | Catherine McDonald |
| MEDICAL ASSESSOR: | Robert Payten |
| MEDICAL ASSESSOR: | Thandavan Raj |
| DATE OF DECISION: | 17 July 2024 |
| CATCHWORDS: | WORKERS COMPENSATION - Workplace Injury Management and Workers Compensation Act 1998; appeal against assessment of whole person impairment in respect of noise induced hearing loss; long work history in varied employment and not all in noisy employment; Shone v Country Energy distinguished; Held – Medical Assessor gave detailed reasons for relying only on findings at 3000 Hz and 4000 Hz; when the hearing loss was not progressive; Medical Assessment Certificate confirmed. |
BACKGROUND TO THE APPLICATION TO APPEAL
On 28 March 2024 David Wilson lodged an Application to Appeal Against the Decision of a Medical Assessor. The medical dispute was assessed by Medical Assessor Henley Harrison, who issued a Medical Assessment Certificate (MAC) on 4 March 2024.
Mr Wilson relies on the following grounds of appeal under s 327(3)(d) of the Workplace Injury Management and Workers Compensation Act 1998 (the 1998 Act) – that the MAC contains a demonstrable error.
The President’s delegate was satisfied that, on the face of the application, the ground of appeal was made out. We conducted a review of the original medical assessment, limited to the grounds of appeal on which the appeal is made.
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.
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).
RELEVANT FACTUAL BACKGROUND
Mr Wilson was employed by Shoalbus Pty Ltd (Shoalbus) as a bus driver. He claimed permanent impairment compensation for 13% whole person impairment (WPI) as a result of hearing loss, with a deemed date of injury of 1 December 2020. Shoalbus did not dispute that it was Mr Wilson’s last noisy employer nor that he suffered noise induced hearing loss, though did dispute that he suffered more than 10% WPI.
The Medical Assessor assessed 5% WPI, after making a deduction for presbycusis and allowing 1% for severe tinnitus. The Medical Assessor determined that only the loss at 3000 and 4000 Hz was consistent with occupational hearing loss.
PRELIMINARY REVIEW
We conducted a preliminary review of the original medical assessment in the absence of the parties and in accordance with the Procedural Direction PIC7.
As a result of that preliminary review, we determined that it was not necessary for Mr Wilson to undergo a further medical examination because the MAC does not disclose error.
EVIDENCE
We have all the documents that were sent to the Medical Assessor for the original medical assessment and have taken them into account in making this determination.
The parts of the MAC that are relevant to the appeal are set out below.
SUBMISSIONS
Both parties made written submissions. They are not repeated in full, but we have considered them.
In summary, Mr Wilson submitted that he had provided a statement setting out a history of exposure to loud noise which showed that 47 years of his 54 year employment history exposed him to noise. He conceded that there was no evidence of exposure in decibels but said that he was exposed to sources of noise which are generally accepted to cause hearing loss. He cited the decision of another medical appeal panel in McNaughton v Engineering & Business Services (NSW)[1] to explain the role of the Medical Assessor and the need to give reasons. He referred to the Medical Appeal Panel decision in Shone v Country Energy[2] (Shone) where the panel included the of loss at the lower frequencies in the assessment with respect to long duration of industrial noise exposure.
[1] [2021] NSWPICMP 159
[2] [2007] NSWWCCMA 18.
Mr Wilson submitted that, by saying that the loss at 2,000 Hz and 3,000 Hz was “the same or almost”, the Medical Assessor conceded that there was a difference, even though he said it was insignificant. Mr Wilson said that the basis for the conclusion had not been made apparent and it was important that the Medical Assessor give reasons where his opinion was different to the other doctors who had provided reports.
Mr Wilson conceded that noise induced hearing loss is typically progressive, affecting the higher frequencies first, so that the loss of 2000 Hz should be less than that suffered at 3000 Hz but he said that the audiograms conducted by each expert showed progressive hearing loss. He also said that the loss at 1,000 HZ and above was consistent with noise induced hearing loss.
In reply, Shoalbus submitted that the Medical Assessor set out a clear path of reasoning for excluding the frequencies below 3000 Hz. It said that the significance of the difference between the loss at 2000 and 3000 Hz was a matter for expert opinion but observed that the loss at 2000 Hz was greater when bone conduction was tested. Shoalbus said that Mr Wilson’s submission that there was a progression between 2000 and 3000 Hz was not supported by medical evidence. It said that Mr Wilson’s contention was no more than a difference of opinion.
FINDINGS AND REASONS
The procedures on appeal are contained in s 328 of the 1998 Act. The appeal is 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.
In Campbelltown City Council v Vegan[3] the Court of Appeal held that an 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] [2006] NSWCA 284.
In Queanbeyan Racing Club Ltd v Burton[4] the Court of Appeal held that an Appeal Panel is not limited to the ground held to have been made out by the delegate but may consider all grounds of appeal raised in the application. However, the Appeal Panel is not permitted to look for errors which are not part of the grounds of appeal on which the appeal is made. We have only considered those grounds specifically raised by the appeal.
[4] [2021] NSWCA 304 at [26].
The MAC
The Medical Assessor said that Mr Wilson had been exposed to loud noise with the potential to damage hearing during his time with Shoalbus and with other employers. The Medical Assessor said:
“I went through the worker's statement with him and confirmed it. He worked for the respondent for 4 years and was exposed to loud noise as described in the statement. He said that the noise was such that in its presence he would have to raise his voice and sometimes shout for someone with normal hearing to understand him at a distance of about 1 metre which suggests that in less than 8 hours the noise had the potential to damage hearing. As he worked 5 hours a shift (5 shifts per week) and noise was present for the large majority of each shift, I concluded that the noise had probably had the potential to damage hearing. Hearing protection could not be worn.
Before that he worked for 6 years for the Premier Transport Group as a bus driver with the same noise exposure as with the respondent.
Before that from 2006 until 2010, he was a sole trader not exposed to loud noise.
Prior to that he worked as a Barman for the North Nowra Pub exposed to loud noise working as a Barman with exposure to band music about once a week and other hotel noise. This was from 2001-2011.
Prior to that from 1999-2000 he worked erecting steel frame kit homes doing basically steel fabrication.
Prior to that his noise exposure was as listed in the statement. His shooting was occupational on the farm operated by his first employer. He has done no other shooting.”
The Medical Assessor described the circumstances in which his audiogram was performed. He said:
“The audiogram showed a bilateral, almost equal sensorineural deafness. The total binaural hearing impairment (BHI) derived from this audiogram is 34.0%. A copy of the audiogram accompanies this report. However not all of this deafness is occupational deafness.”
Summarising the injuries and his diagnosis, the Medical Assessor said there was:
“The audiogram showed a bilateral, almost equal sensorineural deafness. The total binaural hearing impairment (BHI) derived from this audiogram is 34.0%. A copy of the audiogram accompanies this report.”
He said that the audiogram was not consistent with all of the deafness being industrial deafness.
The Medical Assessor set out the matters that he had taken into account in assessing 5% WPI:
“As stated above the history and examination are consistent with a diagnosis of occupational noise exposure but the audiogram is not consistent with this being the sole diagnosis. This is because in noise induced occupational hearing loss the lower frequencies are usually preserved and the hearing loss in the effected frequencies increases in severity with increase in frequency until at least 3000 cps. This in turn is because when damaging acoustic energy (loud noise) enters the inner ear it does so in the region of the basal coil of the cochlea (inner ear) where the sound sensitive hair cells serving the frequencies 3000 up to 6000 cps are situated so they are first damaged and only with further damaging noise exposure are adjacent frequencies damaged and to lesser and lesser degree, the further they are from the initially damaged frequencies. Hence the frequency 2000 cps should be considerably less damaged than 3000 cps which is not the case here. In this case the hearing loss at 2000 cps is the same or almost the same as at 3000 cps (a 5 dB difference is insignificant) so the profile of the audiogram below 3000 cps is not consistent with that diagnosis. I have therefore apportioned the occupational hearing loss to the frequencies 3000 cps and above in which the profile of the audiogram is consistent with being due to occupational noise exposure. This apportionment gives 14.9% BHI before mandatory deduction for presbycusis and 8.7% after such mandatory deduction. The worker's tinnitus is severe and I have made an allowance of 1.0% for that. The foregoing give a resultant total BHI of 9.7% which equals 5% WPI. The rest of the hearing loss is due to an unknown cause or causes, probably at least partly constitutional.”
The reference to cps or cycles per second is equivalent to Hz.
In respect of the reports of Drs Tamhane and Howison the Medical Assessor said:
“Both doctors made differing frequency apportionments to mine despite the audiograms of both showing no real difference between the hearing loss at 2000 cps and 3000 cps. I believe that they should have made a similar frequency apportionment to mine.”
Mr Wilson’s statement
Mr Wilson signed a statement on 13 December 2023. He said he started working as a labourer on a farm after he left school and worked there for two years. He said that he worked up to seven 10 hour shifts each week and was exposed to noise for up to five hours each shift. He then worked for five years as a slaughter floor cleaner in a meatworks where he worked five 10 hour shifts per week and was exposed to noise for the length of his shift “at times”.
Mr Wilson worked as a truck driver for four years, working eight hour shifts on five days per week and was exposed to noise for the full shift “at times.” He then worked full time for about five years as a truck driver for armoured vehicles and said he was exposed to noise for the duration of his shift.
Mr Wilson then operated a milk run for three years and was not exposed to noise. He operated a beer run for about three years where he was exposed to noise but worked only 20 hours per week. Concurrently he worked as a barman in at a club for 20 hours per week and was exposed to noise for about four hours per week.
For three years between 1988 and 1991, Mr Wilson worked as a financial consultant and was not exposed to noise. He then worked for about four years between 1991 and 1995 as a barman and was exposed to the same amount of noise as in his previous job as a barman. After that Mr Wilson worked for five years as a labourer for between 1995 and 2000 and said he was exposed to construction noise for the duration of his shift.
From 2001 Mr Wilson worked for 11 years as a barman at a hotel and was exposed to the same amount of noise as in his previous occupations as a barman. He worked concurrently for four years delivering packaging between 2006 and 2010 and was not exposed to noise. He commenced working as a bus driver in 2010 for another bus operator for up to five shifts per week, each of five hours, and was exposed to noise for up to four hours per shift. From 2016 until his retirement in 2020, Mr Wilson worked in similar conditions for Shoalbus also working up to five shifts per week and being exposed to noise for up to four hours.
Dr Tamhane
Dr Tamhane saw Mr Wilson at the request of his solicitors and reported on 6 April 2023. The history he took is slightly different to that in Mr Wilson’s statement. He said that an audiogram showed “a symmetrical, mild low tone sensorineural hearing loss, deteriorating to become a moderate to severe sensorineural hearing loss”. He said that Mr Wilson had worked for over 35 years employment, which exposed him to noise and had worn hearing protection for only about six years intermittently. He said that Mr Wilson was mainly employed on a full-time basis.
Dr Tamhane assessed 30.1% binaural hearing loss, which after a deduction for presbycusis was 23.9%. He added 2% for severe tinnitus and converted his assessment to 13% WPI. He said:
“Noise induced hearing loss normally affects the 2000Hz, 3000Hz and 4000Hz frequencies but in patients who have had prolonged exposure to loud noise for 30 to 35 years and who have not been able to wear adequate ear protection, the hearing loss can gradually creep into the mid and low tones of 1500Hz, 1 000Hz and 500Hz. Mr Wilson has been exposed to continuous loud noise for over 35 years and has worn hearing protection only intermittently over 6 years of his employment. Considering his history of exposure to continuous loud noise, looking at the configuration of his pure tone thresholds in the speech frequencies in both the ears, after weighing all probabilities and giving him the benefit of the doubt, I would attribute his sensorineural hearing loss in the 500Hz, 1000Hz, 1500Hz, 2000Hz, 3000Hz and 4000Hz frequencies to noise induced hearing loss.”
Dr Tamhane did not explain what he meant by “weighing all probabilities and giving him the benefit of the doubt.”
Dr Tamhane’s audiogram shows the same amount of hearing loss in Mr Wilson’s left ear at 1500 Hz, 2000 Hz, 3000 Hz and 4,000 Hz. The pattern of loss shown on the diagram is not progressive and does not follow the usual shape for noise induced hearing loss. It is basically the same as that obtained by the Medical Assessor.
Dr Howison
Dr Howison reported to Shoalbus’s insurer on 3 July 2023. He also had a different history of noise exposure though accepted that Mr Wilson’s employment with Shoalbus was capable of causing hearing loss. Dr Howison said:
“Noise induced hearing loss is typically bilaterally symmetrical and progressive from the low to the high frequencies and this is because noise damages the inner ear by affecting the higher frequencies first and only with further noise damage are the lower frequencies effected progressively gradually from the higher frequencies to lower frequencies; that is to say 1500 Hz should be affected less than 2000 Hz and 1000 Hz less than 1500 Hz and so on. The progression of hearing loss in the low frequencies needs to be clinically significant if this damage is from exposure to loud noise.
Continuous noise exposure over the years is more damaging than interrupted exposure to noise, which permits the ear to have a rest period. After consideration of the cumulative noise emission levels to which Mr Wilson has been exposed and the shape of the audiogram, I would consider that the frequencies 2000, 3000 and 4000 Hz in the left ear to have been damaged by unacceptable noise levels, as these are the frequencies most affected by industrial deafness and an equal amount of hearing loss should be allowed for loss of hearing in the right ear in accordance with the WorkCover Guides to the Evaluation of Permanent Impairment 4th Edition, 01 April 2016, page 44, section 9.12.”
Dr Howison set out the total assessment of binaural hearing loss of 33.1% Using the figures at 2000 Hz, 3000 HZ and 4000 HZ, Dr Howison assessed 23.5% binaural hearing loss as a result of noisy employment. He deducted 5.5% for presbycusis and added 1% for severe tinnitus, reaching a total of 19% binaural hearing loss or 10% WPI.
Shoalbus also attached an audiogram from Audika undertaken on 3 February 2023 to its Reply. Dr Howison noted that it was more similar audiogram to his than to that of Dr Tamhane.
Consideration
The Medical Assessor was alerted by the standard MAC template to comment on the reports of other practitioners to explain why his assessment was different. He is not required to adopt the findings of another practitioner or choose between those relied on by the parties.[5] He was required to assess Mr Wilson as he presented on the day of the examination[6] and on the basis of the audiogram obtained on that day.
[5] State of New South Wales (NSW Department of Education) v Kaur [2016] NSWSC 346 at [25]-[26].
[6] Guidelines paragraph 1.6.
Mr Wilson’s submission that he worked in noisy employment for 47 of 54 years assumes that any occupational noise exposure is liable to lead to noise-induced hearing loss. We do not consider it likely that he was exposed to noise sufficient to cause hearing loss for that length of time. It is generally accepted that a daily noise dose of 85 dB over an eight hour period is liable to cause hearing loss. Mr Wilson’s history shows that there were periods when he was exposed to that level of noise and periods when he was not. The references to his statement to being exposed to noise for the full extent of his shift “at times” or “for up to…” means that it is not possible to estimate the length of his noise exposure. There were extended periods when Mr Wilson worked part time or periods when he was not exposed to noise for a full shift. We accept that Mr Wilson was exposed to noise for many years but we do not accept, on a proper reading of the statement, that it was as long as 47 years.
While many workers seek to rely on Shone as a basis to argue that all frequencies should be included in an assessment, it is no more than an example of a Medical Appeal Panel decision in which it was appropriate to do so. Shone is a short decision and turns on its own facts. The worker was employed in the same noisy employment for 37 years and in noisy employment for 49 years in total. The Appeal Panel there said:[7]
“The long period of exposure and the progressive loss of hearing in the lower frequencies are, in the view of the Panel, caused by very lengthy noise exposure over a period of 49 years and therefore all of the Applicants hearing loss is due to the work noise exposure.”
[7] At [25].
Notably the Appeal Panel observed that Mr Shone’s losses in the low tones were progressive.
Contrary to Mr Wilson’s submissions, the Medical Assessor did explain why he based his assessment on the loss at 3000 Hz and 4000 Hz only. He explained his reasoning in the passage set out at [24] above, providing detailed information as to the way noise impacts on the structure of the cochlea and how hearing is lost progressively. The Medical Assessor’s description is accurate.
The Medical Assessor’s audiogram does not show a slowly progressive loss nor is the pattern consistent with noise induced hearing loss, which is usually a “ski slope” configuration. There is a “jump” in the loss between 1000 (20dB) and 1500 Hz (65dB) on the left and between 1500 (35dB) and 2000 (75dB) Hz on the right. Using the bone conduction results, the loss on the left is lower at 3000 Hz than at 2000 Hz.
In addition, and in the experience of the medical members of this Appeal Panel, a loss of 65 dB at 2000 Hz is not consistent with noise induced hearing loss. It would generally be anticipated that the loss at 2000 Hz from long noise exposure was in the order of 35 to 40 dB.
The examples in the Guidelines following paragraph 9.16 illustrate this point. Those which illustrate noise induced hearing loss (9.1, 9.2, 9.3, 9.6) show a progressive loss to 4000 Hz., and the smallest gap between 2000Hz and 4000Hz is 20dB. In the case of Mr Wilson the hearing loss in the left ear at 2000Hz of 65dB is the same as at 4000Hz and only 10dB less (75 dB at 2000Hz) than at 4000Hz (85dB) in the right ear. Hearing loss from other causes (such as example 9.4) resulting from a head injury or acute acoustic trauma (9.5) show a different pattern.
For these reasons, we have determined that the MAC issued on 4 March 2024 should be confirmed.
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