You must accept these three hard truths about sone-to-dBA conversion:

To achieve verification, Sone had to traverse the "Schema Labyrinth," a shifting maze of logic gates and primary keys. The Integrity Check

These charts are . They are typically derived assuming a broadband pink noise spectrum. In the real world, ventilation fans, compressors, and data center cooling units do not produce pink noise.

If you need a verified conversion for a specific product without a spectrum, contact the manufacturer for their AMCA 320-11 or ISO 10302 test report. Alternatively, hire an accredited acoustical testing lab to perform a one-hour verification measurement. The cost (typically $500–$1,500) is trivial compared to the liability of a failed noise compliance test.

For most consumer and HVAC equipment (1–8 Sone range), a verified empirical relationship developed by acoustic engineers at the University of Salford and adapted by ASHRAE is: