Which of the following is an event that causes a temporary change in air pressure?

• A. Sound wave
• B. Disturbance
• C. Elastic force
• D. Pulsation

Answer: (B)

The correct choice is the disturbance. A disturbance in the context of sound refers to a change or fluctuation that occurs in the medium, such as air. This change can create temporary variations in air pressure.

When a disturbance happens—like a vibrating object or the movement of air particles—it can lead to a ripple effect that creates areas of compression and rarefaction in the air. This is essentially how sound waves propagate; they transfer energy through the medium by causing localized shifts in pressure that can be perceived as sound by the human ear.

Understanding disturbances is crucial because they are the initial trigger for sound wave generation—each vibration disrupts the surrounding air, leading to these fluctuations in pressure that are fundamental to producing sound.

In contrast, while sound waves are a result of these disturbances, they do not inherently cause changes themselves; they are the means of transmitting the disturbances through the air. Elastic force and pulsation do relate to sound, but they don't specifically denote the initial event that leads to temporary air pressure changes like a disturbance does.