[ \textdBA = 22 + 9.5 \cdot \log_10(\textSones \times 10) + \textFrequency Correction Factor ]
Introduction: The Two Languages of Sound When you browse specifications for a bathroom exhaust fan, a vacuum cleaner, or an industrial air handler, you will inevitably encounter two cryptic units: Sones and dBA (A-Weighted Decibels) . To the untrained eye, these appear to be just different numbers on the same scale. In reality, they are two distinct languages describing two different physical properties of sound.
Or inversely:
The trouble begins when a datasheet provides a rating in Sones, but your building code requires a maximum dBA limit. Or when a client demands a specific “quiet” rating but only understands decibels. This is where the phrase becomes mission-critical.
[ \textPhons = 40 + 10 \cdot \log_2(\textSones) ] sone to dba verified
| Sones | Approx. dBA | | :--- | :--- | | 0.5 | 24 | | 1.0 | 28 | | 2.0 | 34 | | 4.0 | 40 |
The pathway from Sones to dBA is not a straight line—it is a curve that cuts through the frequency domain, the equal-loudness contours, and the specific physics of your sound source. Generic online calculators are fine for rough estimates during early concept design. But when you are writing a specification for a hospital recovery room, a LEED Gold data center, or a luxury apartment building, you cannot afford to be “close enough.” [ \textdBA = 22 + 9
Being “verified” means moving beyond generalized charts and guesswork. It means applying the established psychoacoustic curves (specifically the Fletcher-Munson and Robinson-Dadson equal-loudness contours) to convert subjective loudness (Sones) into objective pressure (dBA) with scientific accuracy.