The loudness of sound depends upon the

Question

Prepp Team · Accepted Answer

Understanding Sound Loudness and Wave Properties

The question asks about the factor that determines the loudness of sound. Loudness is how intense or strong a sound is perceived to be by our ears. It is related to the energy carried by the sound wave.

Let's examine the relationship between loudness and the properties of a sound wave:

Velocity of sound waves: The velocity of sound depends on the medium through which it travels (like air, water, or solids) and the temperature of the medium. It determines how fast the sound travels from one place to another but does not directly control its loudness.
Amplitude of the sound waves: Amplitude is the maximum displacement or distance moved by a point on a vibrating body or wave measured from its equilibrium position. In a sound wave, a larger amplitude means that the air particles are displaced more from their resting positions as the wave passes. A wave with larger amplitude carries more energy. The loudness of a sound is directly related to the square of its amplitude. Therefore, a sound wave with a larger amplitude will be perceived as louder.
Frequency of the sound waves: Frequency is the number of complete oscillations or vibrations per unit of time. It is measured in Hertz (Hz). Frequency determines the pitch of the sound – a higher frequency corresponds to a higher pitch (like a whistle), and a lower frequency corresponds to a lower pitch (like a drum). Frequency does not determine loudness.

Based on the properties discussed, the loudness of sound primarily depends on the amplitude of the sound waves.

Comparing Sound Wave Properties and Perception

Wave Property	Definition	Related Perception of Sound	Impact on Loudness
Amplitude	Maximum displacement from equilibrium	Loudness/Intensity	Directly related; higher amplitude means louder sound
Frequency	Number of vibrations per second	Pitch	Determines whether sound is high or low pitched; does not determine loudness
Velocity	Speed of wave propagation	How fast sound travels	Depends on the medium; does not determine loudness

The energy of a sound wave is proportional to the square of its amplitude. Since loudness is related to the energy of the sound wave, it is directly dependent on the amplitude.

Conclusion on Sound Loudness

The loudness, or intensity, of a sound is determined by the amplitude of the sound wave. A larger amplitude means a louder sound because the wave is carrying more energy.

Revision Table: Key Sound Concepts

Term	Description	Related Property
Loudness	Perception of sound intensity	Amplitude
Pitch	Perception of sound frequency	Frequency
Speed of Sound	How fast sound travels	Medium, Temperature

Additional Information on Sound Waves

Sound waves are longitudinal waves, meaning the particles of the medium vibrate parallel to the direction of wave propagation. When we talk about the amplitude of a sound wave, we are referring to the maximum change in pressure or density of the medium from its average value, caused by the wave. This pressure variation is directly related to the displacement amplitude of the particles.

The intensity of sound is a physical measure related to loudness. It is defined as the power per unit area carried by the sound wave. Intensity is proportional to the square of the amplitude (\(I \propto A^2\)) and also proportional to the square of the frequency (\(I \propto f^2\)) and the density of the medium and the wave speed. However, when the question asks what the loudness depends upon among the given options related to the wave itself, the primary determinant directly related to the energy and perceived loudness is the amplitude.

The unit of loudness level is the decibel (dB), which is a logarithmic scale comparing the intensity of a sound to a reference intensity.