| work Baa BC Clinical Opinion (continued)

Worker last name First name Middle initial | WorkSafeBC claim number
HOLAND MARK 42647461

few hours after the acoustic event (McFerran & Baguley, 2007).

In this worker’s case, he reported exposure to noise from computer server fans. Examples of acoustic events
that are intense enough to potentially result in acoustic trauma include explosions and gunshots. While the fans
were subjectively loud, it would not have reached levels capable of causing acoustic trauma.

e The worker's employer conducted a noise survey in the training simulation room on March 6, 2026. The
noise data taken from the workstation that was approximately 1 meter from the two server racks indicated
an average exposure level of 57.6 dBA and a peak of 86.7 dBC. The measured noise levels in the
training simulation room are well below hazardous levels.

e This is consistent with WorkSafeBC noise data collected in various work environments (e.g., BC Ferry
data center and a central computer processing area of a large hospital) with similar noise sources, which
also indicate exposures below hazardous levels. These measurements take into consideration noise from
servers, network equipment, and air conditioning equipment.

These measurements have been collected using appropriate equipment and analyzed by professionals trained
and experienced in noise measurement methodology (e.g. Occupational Hygienists).

There are pre-incident industrial audiograms on file from October 2023 to September 2025. There is also a post-
incident audiogram from January 30, 2026. A comparison of the pre-incident results from September 2025 and
the post-incident results from January 30, 2026 show that the worker’s hearing thresholds have remained stable.
Differences of 0 to 10 dB are within test-retest variability and are not considered to be significant. Therefore,
there is no evidence of any significant changes in hearing thresholds since September 2025.

The described incident and evidence on file are not consistent with acoustic trauma.

Further, the noise from the computer server fans was not sudden or unexpected. The worker also did not report
any symptoms until around one week after the training course began. Overall, the incident is not consistent with
acoustic shock either.

As per Dr. Zahabi, he noted that the worker’s symptoms do not appear to be ear, nose, and throat of origin.

Regarding the worker’s report of headache/migraines and the work-related noise exposure:

The worker's pre-existing history of migraines is non-occupational. As mentioned in the medical records and in
his correspondence with the instructor, his sensitivity to noise is also pre-existing and non-occupational.

Two known triggers for the worker’s migraines are stress and lack of sleep. As noted above, Dr. Zahabi
suspected that the work environment might have also been a trigger to the worker’s pre-existing migraine
condition. However, as per the employer's noise survey, the average noise exposure level at the worker’s
workstation was 57.6 dBA. While the noise was subjectively loud and might have been perceived as unpleasant

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