Sone 363 [top] -

The is a unit of loudness level that aligns with the equal‑loudness contour for a 1 kHz pure tone. By definition, a 1 kHz tone at X dB SPL has a loudness level of X phon. For other frequencies, the required SPL to achieve the same phon value is read off the Fletcher‑Munson curves (or ISO 226 equal‑loudness contours).

To reach 363 sones, we must understand the exponential relationship between dB and Sones. The formula for converting dB to Sones (for a 1 kHz tone) is approximately: sone 363