# The loudness of sound is determined by its _____________ (A) Amplitude (B) Frequency (C) Velocity (D) Source

The loudness of sound is a phenomenon of a sound depending on the amplitude of the sound wave. If the amplitude of the sound wave is large, then the sound is said to be loud. The loudness of sound is directly proportional to the square of the amplitude of vibration, and it is expressed in decibel (dB). Therefore, sounds above 80 dB become noise to human ears. Therefore, the correct option is (A)