One decibel approximates the smallest loudness change humans can perceive

Evidence

The factor of 10 arises because this makes the result a number in which an integer change is approximately equal to the smallest change that can be perceived by the human ear. A factor-of-10 change in the power density ratio is called the bel; in Equation 1.18 this would result in a change of 10 in the outcome. The integer unit that results from Equation 1.18 is therefore called the decibel (dB). — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 180

Categorization

• DEFINE: Grounds the decibel unit in a perceptual fact about the human ear — a good anchor for explaining why the scale is logarithmic.
• XREF: Directly illuminates the reader’s stated goal of understanding how sound mechanics produce perceptual phenomena, bridging objective intensity to subjective hearing.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 180