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ISO 1999 acoustic standard: revised version containing errors is averted

Illustration der Schallwellen, die das Ohr einer Person erreichen © peterschreiber.media – stock.adobe.com

2025-08-04

ISO 1999:1990, Acoustics – Estimation of noise-induced hearing loss, has long been a recognized standard for determining and assessing workers’ exposure to noise, and is also referenced in EU legislation (Directive 2003/10/EC). The standard was scheduled for revision in 2024. However, the draft of the revision contained scientifically incorrect information that would have led to protective measures, such as hearing protection, being mandatory at lower noise thresholds than previously (e.g. during use of a vacuum cleaner, work by aircraft cabin crew). No reasoning exists for these measures.

Together with the Institute for Occupational Safety and Health of the DGUV (IFA) and the Federal Institute for Occupational Safety and Health (BAuA), KAN drew up a statement on these methodological errors, and invoked the unanimous vote of the stakeholders in occupational safety and health (see KANBrief 4/24: ISO 1999: not all quiet on the acoustics front). The draft standard was rejected in the autumn of 2024 by both the German mirror committee and ISO.

However, following minor amendments to the content, the standard was then to be transposed into an international Technical Specification (ISO/TS). In the survey on changing the form of the document, the IFA once again drew attention in the mirror committee to the unanimous vote of KAN. Germany then voted against the amendment, although this did not prevent the TS from receiving majority support internationally. However, it was rejected, its content still scientifically incorrect, in the ISO consultation in 2025. Thanks to their criticism, which was also voiced internationally on many occasions, the occupational safety and health stakeholders were thus ultimately able to avert the requirement for protective measures to be taken even at low noise levels, despite the need for these measures not being reasoned from a prevention perspective owing to methodological errors.