Company identification and selection, and data collection process (noise risk assessment report submission)

The participating companies were conveniently selected, informed by a risk-based criteria of confirmed historic NIHL incidence, determined through the evaluation of sustainability reports. The final selected companies were identified and selected using a longitudinal study of 20 manufacturing and utilities companies, the method of which has been previously reported by Rikhotso et al. (2023; 2022a). Company A is from the utilities sector, whereas Companies B (petroleum refining), C (radioisotope manufacturing) and D were from the manufacturing sector. Companies A and C had 11 and 6 operational units, respectively. Both Companies B and D had two operational units, each. The included companies submitted recent electronic noise risk assessment records for each operational unit for evaluation, which were securely stored in a password-protected folder by the primary investigator (O.R.) upon receipt.