How is a Sound Loud or Soft?

How loud or soft a noise is depends on the noise's intensity. If a sound has a higher intensity, the louder the ear will hear the sound to be. The intensity of a sound is decided by the amplitude of the vibrations. The more amplitude, the more intensity. The more intensity, the more loudness. The unit of intensity is the decibel (dB). Loudness is measured in phons, but is not commonly used.

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