Intensities are measured in which unit?

• A. decibels (dB SPL)
• B. decibels (dB HL)
• C. pascals (Pa)
• D. Hertz (Hz)

Answer: (A)

Intensities are expressed using a logarithmic scale that matches how we perceive loudness, specifically decibels of sound pressure level (dB SPL). This expresses the actual sound pressure relative to a standard reference pressure of 20 μPa, with the value calculated as 20 log10(p/p0). The log scale compresses the vast range of pressures into a manageable range and ties the measurement to perceptual loudness, making comparisons meaningful across different sounds. Pascals measure the physical pressure itself, not a level or scale, so they don’t convey how loud something seems. Hertz measures frequency (how often the pressure varies per second), not intensity. In audiology, dB HL exists for hearing thresholds, but it’s a relative level used for audiometric assessment, not a direct measure of physical intensity.