Question

Loudness of sound is determined by its____________.
(A) Amplitude
(B) Frequency
(C) Velocity
(D)Source

Answer 1

Hint: Loudness is a property that depends on the sensitivities of the ear. It may vary from person to person. Loudness refers to how large is the sound, coming from any source.

Complete Answer:
We feel the louder sounds that are produced by the larger vibration of the source. The vibration of the source can be considered as the origin of the sound. For example, if we move the loudspeaker cone forward and backward for a larger distance it produces the greater disturbance in other words the larger vibration of air, thus we hear the louder sound from it.
The vibrations or the disturbance of the source for example air depends on the amplitude of the source.
We know that the amplitude for a vibrating body is defined as the maximum distance traveled by a wave away from its mean equilibrium position. The loudness of the sound is directly proportional to the square of the amplitude of vibration.
Generally, loudness if found to be a subjective property .i.e. its sensitivity varies from person to person. Our ear responds to the sound differently. A very large increase in amplitude is considered to be the small increase in the loudness. If the amplitude of the sound is low, the sound is said to be soft but if the amplitude of the sound is high then it is said to be loud.
Thus, the loudness of a sound depends on the amplitude which determines its loudness and volume.

$\therefore$ Loudness of the sound depends on its Amplitude. Hence, option (A) is the correct option.

Additional information:
The day to day conversation between people takes place around 60dB and sound above the range of 80 dB is regarded as noise in case of a human being.
The sound produced during normal breathing is of 10Db and the whisper is of 30dB
It should be noted that the loudness of a sound depends on its amplitude which in turn depends on its intensity. Intensity can be defined as the amount of energy passing per unit time through a unit area which is perpendicular to the direction in which the sound is traveling. The unit of sound is a decibel.

Note:
It should be noted that loudness is different from the pitch. loudness depends on amplitude similarly pitch depends on its frequency. The quality of voice of different individuals depends on the pitch of the sound.
Here, students should understand the different properties of sound like amplitude, frequency,etc.so that they can answer such questions very easily. Students should understand that the intensity and loudness of sound are not the same. Loudness is the sensitivity of the ear. On the other hand intensity of sound depends on the amount of sound wave passing through the unit area.