What is generally taken to be the minimum sound power change that humans can detect?

Answer 1

Short answer: An increase of 26% can be detected as a louder sound to humans. Which is the definition of one decibel. Obviously, individuals vary in that, though.

1 decibel is the typical threshold for humans detecting a change in sound level ("volume") That is a multiplier of 1.2589.... which is the tenth root of ten.

a 20 dB increase is 1.2589^20 = 100 times the sound intensity.

Divide dB by ten. Use the answer as the exponent in 10^X. That is the ratio of the two sounds.

10 dB means 10^1=10 times more.
20 dB means 10^2=100 times more.
30 dB means 10^3=1,000 times more.
40 dB means 10^4=10,000 times more.
Etc.

Oh, and the d is small just like the c in cm or the k in kg. The B is capitalized for Alexander Graham Bell.

Hope that helps.