[ \textSones = 2^\left(\frac\textPhons - 4010\right) ]

1. Executive Summary

| Unit | Measures | Scale | Human Perception | |------|----------|-------|------------------| | | Perceived loudness | Linear (2 sones = twice as loud) | Directly proportional | | Decibel (dB SPL) | Sound pressure (physical) | Logarithmic | Not proportional | | Phon | Loudness level | Logarithmic (matches dB SPL at 1 kHz) | Scale for matching loudness |