Loudness perception is the psychological correlate of which physical property?

• A. Amplitude
• B. Frequency
• C. Time
• D. Timbre

Answer: (A)

Loudness is the perceptual result of how much energy a sound wave carries, which corresponds to its amplitude. When the air particles fluctuate with larger displacements, the sound carries more energy and the listener experiences a louder sensation. The relationship isn’t perfectly linear because the human ear isn’t equally sensitive to all frequencies, and loudness depends on both amplitude and frequency in practice (as shown by equal-loudness contours).

In contrast, frequency is about pitch, not how loud something is. Time relates to duration or how loudness changes over time, but the primary physical property that drives loudness is amplitude. Timbre describes the quality or color of the sound determined by its harmonic content, not its overall loudness.