Question

Which wave property determines loudness?

Answer 1

Hint:The sound propagates as a longitudinal wave. In the longitudinal motion, the particles of the medium vibrate back and forth and move in the direction of propagation of the wave. The loudness can be expressed by the vibrations of air molecules from their mean position. Recall the property that expresses the vibration of a particle from its mean position.

Complete answer:
We know that the sound travels in the form of waves. As we know there are two types of waves: longitudinal waves and transverse waves. In the longitudinal motion, the particles of the medium vibrate back and forth and move in the direction of propagation of the wave. In sound, the particles of air vibrate due to compression and rarefactions of the molecules. Therefore, we can say the sound wave is a longitudinal wave. We describe the wave by the properties such as amplitude, wavelength, velocity, frequency and time period.

We have seen that the loudness is the property of sound which measures the magnitude of hearing sensation reaching the ears per second. Therefore, the loudness can be expressed by the vibrations of air molecules from their mean position. If the vibration of the molecules is the maximum then we can hear the sound louder. We know that the amplitude of the wave is the maximum vibration of the particle from the mean position. Therefore, we can say that the amplitude of the longitudinal wave determines the loudness of the sound. The loudness of the sound is proportional to the square of the amplitude.

Note: The amplitude of the sound wave is the same as the amplitude of the vibrations produced by the body which is producing the sound. The frequency of the wave does not measure the loudness. The frequency of the wave measures the pitch of the sound.