The unit of sound intensity is the _______.

• A. Decibel
• B. Watt per cm squared
• C. Newtons per cm squared
• D. Pascals

Answer: (A)

Sound intensity level is described with a logarithmic unit because the actual energy flow of sound spans many orders of magnitude. The decibel expresses how strong a sound is relative to a reference level, using the formula L_I = 10 log10(I/I0). This makes it practical to compare loudness across tiny to extremely loud sounds and aligns well with how humans perceive changes in loudness. In everyday acoustics, we report levels as decibels, not the raw physical flux. The other options describe actual physical quantities—W/m^2 for intensity, N/cm^2 as a force-per-area (similar to pressure), and Pascals as pressure—but they are not the standard units used to express the loudness level of a sound.