Singh v Air Liquide Australia Limited

DETERMINATION OF APPEAL PANEL
CITATION:	Singh v Air Liquide Australia Limited [2024] NSWPICMP 156
APPELLANT:	Alfred Mahendra Singh
RESPONDENT:	Air Liquide Australia Limited
APPEAL PANEL
MEMBER:	R J Perrignon
MEDICAL ASSESSOR:	Thandavan Raj
MEDICAL ASSESSOR:	Brian Williams
DATE OF DECISION:	19 March 2024
CATCHWORDS:	WORKERS COMPENSATION - Appeal from assessment of whole person impairment; whether Medical Assessor erred in finding that hearing losses below 2000Hz, including 1500Hz, 1000Hz and 500Hz, were not caused by occupational noise exposure; whether the audiometer used was properly calibrated; whether he erred in calculating an allowance for presbycusis; Held – Medical Assessment Certificate confirmed.

BACKGROUND TO THE APPLICATION TO APPEAL

The appellant worker, Mr Singh, appeals from the Medical Assessment Certificate of Medical Assessor Howison dated 21 November 2023.
The Medical Assessor assessed a 3% whole person impairment (binaural hearing impairment) as a result of injury on 27 September 2018 (deemed date). He assessed hearing losses at below 2000Hz at zero, because he was not satisfied that those losses were caused by occupational noise exposure.
In his Table, the Medical Assessor added together binaural hearing impairment at all frequencies totalling 31.5%. After deducting 16.5% for ‘non-related’ losses below 2000 Hz, and 8.3% for presbycusis, he assessed an adjusted binaural hearing impairment (BHI) of 6.7%, which converts to 3% whole person impairment.
Mr Singh requests re-examination by the member of the Appeal Panel, submitting that the assessment was affected by demonstrable error or the application of incorrect criteria in three respects:
(a)    hearing loss was not measured in accordance with the Guidelines because the Medical Assessor failed to provide ‘a reading on the hearing level dial of an audiometer that is calibrated according to Australian Standard AS 2586 1983’;
(b)    the Medical Assessor wrongly found that losses at 1500hz, 1000hz and 500hz were not noise-induced, and wrongly excluded those losses from his calculations of BHI, and
(c)    his calculation of 8.3% for presbycusis was in error because it was ‘vastly higher than the assessment of Dr Scoppa and Dr Harrison’, and ‘no calculation [was] provided’ with reference to the binaural tables RB 500-4000 (NAL publication, pp 11-16) in accordance with the Guidelines at [9.9].
The Appeal Panel conducted a preliminary review of the Medical Assessment Certificate in the absence of the parties and in accordance with the NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment (4th edition) (the Guidelines).

Submissions

The parties made written submissions which have been taken into account. The appellant’s submissions are summarised above. The respondent submits in summary as follows.
(a)    the Medical Assessor stated the audiometer was calibrated, but did not identify the standard by which is was calculated. His reference to AS/NZS 1269 was not a reference to the audiometer, but to the standard by which the sound treatment of the room had been performed. There is no evidence that the audiometer was not appropriately calibrated;
(b)    both the Medical Assessor and Dr Harrison, on whose assessment the respondent relied, excluded frequencies below 2000Hz from their calculations of BHI. Dr Scoppa, on whose assessment the appellant relied, included hearing loss at 1500Hz, but excluded frequencies below that. However, noting that the losses from 500Hz to 2000Hz were ‘relatively flat’, he accepted that his audiogram was ‘atypical for noise induced hearing loss’. The decision to include or exclude losses in the lower frequencies is a matter for clinical judgment, based on the extent and duration of noise exposure and a comparison of losses in the lower and higher frequencies. The Medical Assessor gave reasons for disagreeing with Dr Scoppa’s conclusions, and
(c)    the Medical Assessor was not bound by the calculation of presbycusis made by Dr Scoppa (6.8%) or Dr Harrison (6.2%) some four and three years earlier respectively. Deductions for presbycusis are based on the worker’s age and the time elapsed since the last noisy employment, both of which had changed in the interim. None of the three clinicians provided a calculation of presbycusis. The Medical Assessor correctly referred to [9.10] of the Guidelines as the basis for his calculation.

Calibration of audiometer

Medical Assessor Howison examined the appellant on 9 November 2023. The appellant was then 75 years of age, having ceased his employment with the respondent in 2018. It is not disputed that the respondent was the last noisy employer.
At [7], the Medical Assessor diagnosed bilateral high tone sensori-neural noise induced hearing loss.
The Guidelines at [9.8] provide:
“Hearing threshold level for pure tones is defined as the number of decibels above standard audiometric zero for a given frequency at which the listener’s threshold of hearing lies when tested in a suitable sound attenuated environment. It is the reading on the hearing level dial of an audiometer that is calibrated according to Australian Standard AS 2586 1983.”
The pronoun ‘It’ in the second sentence is a reference to ‘Hearing threshold level’. The second sentence means that hearing thresholds are established by the hearing level dial on an audiometer, and that the audiometer must be calibrated in accordance with the relevant Australian Standard. The hearing level dial measures hearing thresholds at particular frequencies. Once the audiometer itself is calibrated, all the readings on the dial reflect that calibration. There is no means of separately calibrating the dial.
At [5] of the Medical Assessment Certificate, the Medical Assessor indicated – emphasis added:
“Pure tone audiometry was carried out in a suitable sound treated room that has been tested and shown to meet specifications laid out in AS/NZS 1269 using a calibrated audiometer.”
Giving these words their ordinary meaning, we agree with the respondent that the Medical Assessor was referring to the standard by which the room was treated for sound attenuation, rather the standard by which the audiometer was calibrated. The Medical Assessor states his assessment used the method of assessment in the NSW Workers Compensation Guidelines for the evaluation of Permanent Impairment 4^th Edition, 1 March 2021 which are the current Guidelines. The Medical Assessor states he used a calibrated audiometer.
There is no evidence that the audiometer was not calibrated in accordance with Australian Standard AS 2586 1983, as required by [9.8]. We are not satisfied that it was calibrated incorrectly. This ground of appeal fails.

Exclusion of losses at 1500Hz, 1000Hz and 500Hz

At [10b], the Medical Assessor explained his finding that losses at 1500 and below were not noise induced:
“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 Singh has been exposed and the shape of the audiogram, I consider that the frequencies 2000, 3000 and 4000 Hz in each ear have been damaged by unacceptable noise levels …”
The Medical Assessor’s reasons adequately explain why he excluded hearing losses at the 3 frequencies below 2000Hz, that is at 500, 1000 and 1500 Hz. He considered that the pattern of the losses below 2000Hz was inconsistent with the pattern of occupational noise induced hearing loss. The Medical Assessor states that after consideration of the nature and duration of occupational noise exposure and the nature and extent of the hearing losses at those three frequencies below 2000 Hz, he found that the hearing losses at those three frequencies below 2000 Hz are unrelated to his occupational noise exposure. In our view, the conclusion to which he came was reasonably open to him. We add that, in our view, on the history taken by the Medical Assessor, and having regard to the pattern of losses below 2000Hz, the nature and extent of the occupational noise exposure is incompatible with the nature and extent of the losses at the three frequencies below 2000 Hz. Having regard to all those factors, we agree that losses below 2000Hz are unlikely to have been caused by his occupational noise exposure.
The Medical Assessor, Dr Scoppa and Dr Harrison all agreed that losses at 500Hz and 1000Hz were not noise induced. Dr Scoppa was the only one to find that losses at 1500Hz were noise induced. The Medical Appeal Panel notes that neither Dr Scoppa, Dr Harrison or the Medical Assessor found that the hearing losses at all three frequencies below 2000 Hz, namely 500, 1000 and 1500 Hz, are due to his occupational noise exposure.
Dr Scoppa had assessed the worker four years earlier in October 2019. Dr Harrison did so in July 2020, well over three years earlier. The Medical Assessor was not bound to accept either of their assessments. His duty was to assess hearing loss as he presented on
9 November 2023. As he indicated at [10c], his audiogram was different from each of theirs.
With respect to Dr Harrison’s assessment, he explained:
“I agree with Dr Harrison accepting that the frequencies 2000, 3000 and 4000 Hz in each ear have been damaged by loud industrial noise and I have used the air conduction studies at those frequencies in the calculations.”
With respect to Dr Scoppa’s assessment, he explained:
“I agree with Dr Scoppa that the frequencies 500 and 1000 Hz have not been affected by loud industrial noise and I disagree with Dr Scoppa including the frequency 1500 Hz as being damaged by loud industrial noise.”
Dr Scoppa examined the worker twice: first on 15 October 2019, and later on
18 October 2021. In his first report of 17 October 2019, he concluded:
“In my opinion Mr Singh's hearing loss is not entirely due to industrial deafness because of unacceptable low tone involvement. Industrial deafness typically causes an increasing hearing loss from low to high tones with relative sparing of the low tones in comparison to the high tones.
After taking into account Mr Singh's history of occupational noise exposure, the number of years that he has worked in noise, and the audiometric configuration shown on my audiogram I have formed the opinion that the hearing loss in both ears at 2000Hz and above is due to industrial deafness and that the hearing loss in both ears below 2000 Hz is unrelated to industrial deafness for the reasons discussed above.”
After examining him again on 18 October 2021, Dr Scoppa expressed a different view with respect to losses at 1500Hz:
“After taking into account Mr Singh's history of occupational noise exposure, the number of years that he has worked in noise, and the audiometric configuration shown on my current audiogram I have formed the opinion that the hearing loss in the left ear at 1500 Hz and above and an equal amount of loss in the right ear is due to industrial deafness, and that the remaining bilateral hearing loss is of unknown cause.
It is well known that industrial deafness typically causes a bilaterally symmetrical sensorineural hearing loss from low to high tones with relative sparing of the low tones in comparison to the high tones, with the maximal loss occurring at 4000 and 3000 Hz.
I note that there is a relatively flat loss from 500 Hz to 2000 Hz shown in the left ear on my current audiogram, and in my opinion this audiometric profile is inconsistent with the losses at 500 and 1000 Hz in the left ear being due to industrial deafness.
There is also an asymmetrical mixed hearing loss shown on my current audiogram involving the right ear that is not due to industrial deafness as industrial deafness is typically bilaterally symmetrical. The cause of the asymmetrical hearing loss is unknown, and I would recommend referral to a treating ENT surgeon for further investigation.”
He added:
“I note that comparison of my current audiogram with my previous audiogram that I obtained on 15 October 2019 shows that the right ear thresholds have remained relatively stable, but the left ear thresholds have improved significantly. The loss in the right ear on 15 October 2019 was 56.6%, and on 18 October 2021 was 51.9%. On the other hand the loss in the left ear on 18 October 2019 was 58.4%, whereas on 18 October 2021 it had improved to 39.9% after correction for presbycusis.
I have no explanation for the change in threshold in the left ear, but it is well known that there are many causes of fluctuating hearing loss, although the history obtained from Mr Singh is not suggestive of any such causes such as Meniere's disease, perilymph fistula, or auto immune disease.
Nonetheless there is a very significant difference between my current audiometric findings and the audiogram of Dr Harrison, and in cases such as this matter where audiometric thresholds are very inconsistent the only way that the issue can be resolved is to cany our a CERA audiogram that provides objective evidence of probable true thresholds on the date of testing, and if the issue cannot be resolved then my recommendation is that Mr Singh be referred for a CERA test.”
After discussing differences between his audiogram and that of Dr Harrison, Dr Scoppa concluded:
“I am at a loss to explain this unusual matter of variable and what appears to be fluctuating hearing loss at different times of testing, and if agreement between the parties cannot be reached I would recommend as above that Mr Singh be referred for a CERA test that would provide objective evidence of the hearing loss status on the day of testing.”
As indicated, it was the task of the Medical Assessor to examine the worker as he presented on 9 November 2023. That presentation is reflected in the audiogram which the Medical Assessor produced, and which formed the basis of his assessment. That audiogram differed from the one on which Dr Scoppa based his view. In our view, based on the results of the Medical Assessor’s audiogram, the conclusion to which he came - that hearing losses below 2000Hz were not noise induced – was both reasonably open to him, and correct. There is no medical evidence available to the Medical Appeal Panel that justifies a finding that any of the hearing losses below 2000 Hz (that is, 500, 1000 and 1500 Hz) are caused by occupational noise exposure.
We can discern neither demonstrable error nor the application of incorrect criteria.

Presbycusis

The Guidelines provide at [9.9]:
“Evaluation of binaural hearing impairment is determined by using the tables in the 1988 NAL publication with allowance for presbyacusis according to the presbyacusis correction table, if applicable, in the same publication.”
And at [9.10]:
“Presbyacusis correction (NAL publication, p 24) only applies to occupational hearing loss contracted by a gradual process (eg occupational noise-induced hearing loss and/or occupational solvent-induced hearing loss).”
The appellant submits that the allowance for presbycusis was in error because it was vastly higher than that of Dr Scoppa and Dr Harrison made years earlier. For the reasons already given, the Medical Assessor was not bound to accept the allowances they made. For the reasons which follow, his allowance for presbycusis was correct.
The appellant also submits that the Medical Assessor erred by omitting to provide a ‘calculation’ of presbycusis. At [10b] under the heading, “Assessment of WPI”, he indicated that he had calculated presbycusis in accordance with [9.10] of the Guidelines. As indicated, [9.9] required the use of the presbycusis correction table in the 1988 NAL publication.
Table P at Appendix 5 to the 1988 NAL publication sets out the percentage hearing loss attributable to presbycusis for males and females, depending on their age. When the Medical Assessor assessed the worker, he was 75 years of age. When Dr Harrison and Dr Scoppa did so, Mr Singh was younger. Different percentages are prescribed by Table P for different ages.
The percentage for males aged 75 is 8.3. The Medical Assessor applied this percentage for presbycusis. He was correct to do so.

Conclusion

For the reasons given, we can discern neither demonstrable error nor the application of incorrect criteria in respect of any of the three grounds of appeal. There is no basis for a re-examination. The appeal is dismissed, and the Medical Assessment Certificate of Medical Assessor Howison is confirmed.

[2024] NSWPICMP 156

19 March 2024