The image in the far field is less bright due to which phenomenon?

The image in the far field is less bright due to which phenomenon?

• A. Sound attenuation
• B. Propagation speed variation
• C. Refraction
• D. Diffraction

Answer: (A)

The main concept here is energy loss as waves travel, known as attenuation. As sound propagates through a medium, it loses energy to the surroundings through absorption, scattering, and other processes. This loss reduces the wave’s amplitude over distance, so by the time the signal reaches the far field, the intensity is lower and the image looks less bright. Other phenomena can move or spread the energy without inherently removing it: variations in propagation speed mainly change timing, refraction bends the path, and diffraction redistributes energy around obstacles. While these can affect how the energy is distributed, attenuation is what directly makes the far-field image dimmer.

The main concept here is energy loss as waves travel, known as attenuation. As sound propagates through a medium, it loses energy to the surroundings through absorption, scattering, and other processes. This loss reduces the wave’s amplitude over distance, so by the time the signal reaches the far field, the intensity is lower and the image looks less bright.

Other phenomena can move or spread the energy without inherently removing it: variations in propagation speed mainly change timing, refraction bends the path, and diffraction redistributes energy around obstacles. While these can affect how the energy is distributed, attenuation is what directly makes the far-field image dimmer.