Intensity is measured in which unit?

Intensity in the context of sound is measured in decibels (dB). This unit quantifies the level of sound intensity relative to a reference level, typically the threshold of hearing. The decibel scale is logarithmic, meaning that each increase of 10 dB corresponds to a tenfold increase in sound intensity. This scale is particularly useful in audiology and sound measurement because it enables a wide range of intensities to be represented in a manageable way.

The other units listed have different applications: Hertz (Hz) measures frequency, which relates to pitch rather than intensity; Amperes (A) denote electrical current; and Joules (J) measure energy. Therefore, the appropriate choice for sound intensity measurement is decibels.