What unit is used to measure sound intensity (loudness)?

The unit used to measure sound intensity (loudness) is the decibel, abbreviated as dB. This logarithmic unit quantifies the intensity of sound by comparing it to a reference level. The decibel scale is widely used because it allows for a more manageable representation of the vast range of sound intensities that humans can hear. For example, normal conversation might be around 60 dB, while a rock concert could exceed 100 dB.

Other measurement units mentioned, such as cycles per second (cps) and hertz (Hz), are used to describe frequency rather than intensity. Frequency refers to how many cycles of a sound wave occur in one second, which affects the pitch of the sound rather than its loudness. Lux, on the other hand, measures illuminance or light intensity, making it irrelevant in the context of sound measurement. Thus, decibels are the appropriate unit for quantifying how loud a sound is perceived.