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.
Loudness refers to how loud or soft a sound seems to a listener. The loudness of sound is determined, in turn, by the intensity of the sound waves. Intensity is a measure of the amount of energy in sound waves. The unit of intensity is the decibel (dB). Thus, the intensity of sound waves determines the loudness of sounds. Intensity results from two factors: the amplitude of the sound waves and how far they have traveled from the sound source.
- Amplitude is a measure of the size of sound waves.
- It depends on the amount of energy that started the waves.
- Greater amplitude waves have more energy and greater intensity, so they sound louder.