Sound is a form of energy that travels in waves through a medium, such as air or water. Sound waves are produced by vibrating objects, such as a guitar string or a speaker. The energy of a sound wave is related to two main factors: its amplitude and its frequency.
Amplitude: The Height of the Wave
The amplitude of a sound wave is the maximum displacement of the medium from its equilibrium position. In other words, it is the height of the wave. The greater the amplitude, the more energy the sound wave has. For example, a loud sound has a high amplitude, while a soft sound has a low amplitude.
The amplitude of a sound wave can be measured by the pressure it exerts on the medium. The pressure is the force per unit area that the wave applies to the medium. The greater the pressure, the more energy the sound wave has. For example, a loud sound has a high pressure, while a soft sound has a low pressure.
According to OpenStax, the energy of a sound wave is proportional to its amplitude squared. This means that if the amplitude of a sound wave is doubled, its energy is increased by four times.
Frequency: The Number of Cycles per Second
The frequency of a sound wave is the number of cycles or oscillations that the wave completes in one second. In other words, it is how fast the wave vibrates. The frequency of a sound wave is measured in hertz (Hz), which is equal to one cycle per second. For example, a sound wave with a frequency of 440 Hz completes 440 cycles in one second.
The frequency of a sound wave is related to its pitch, which is how high or low the sound is perceived by the human ear. Higher frequency sounds have higher pitches, while lower frequency sounds have lower pitches. For example, a whistle has a high frequency and a high pitch, while a drum has a low frequency and a low pitch.
The frequency of a sound wave also affects its energy, but not as much as its amplitude. According to LibreTexts, if two mechanical waves have equal amplitudes, but one wave has a frequency equal to twice the frequency of the other, the higher-frequency wave will have a rate of energy transfer (or power) four times as great as the rate of energy transfer of the lower-frequency wave.
Conclusion
The energy of a sound wave is most closely related to its amplitude and frequency. The greater the amplitude and frequency, the more energy the sound wave has. The amplitude and frequency also determine the loudness and pitch of the sound, respectively. By understanding these factors, we can better appreciate how sound works and how it affects us.