Measurement of Sound Intensity or Loudness
Puzzle 2 of Recording an Album Medium Pack
Question is: Measurement of Sound Intensity or Loudness
and the answer is: DECIBEL
Word Meaning:
DECIBEL — A common measure of intensity ratio (e.g. for sound) that is one tenth of a bel on the logarithmic intensity scale. It is defined as dB = 10 log₁₀(P₁ / P₂), where P₁ and P₂ are the relative intensities.
Definitions from Wiktionary.