What is a key feature that increases the effectiveness of noise barriers?

The effectiveness of noise barriers is significantly influenced by their height and continuous structure. A taller barrier is generally more effective at blocking sound because it creates a greater obstruction to the noise waves emanating from the source. Sound travels in a straight line, so a barrier that is high enough to intercept these waves can effectively reduce their intensity before they reach the areas behind the barrier.

Moreover, a continuous structure without gaps ensures that sound does not pass through openings, which would diminish the barrier's overall effectiveness. Any breaks or discontinuities can allow sound to leak through, potentially reducing the barrier's ability to shield the protected area.

In contrast, factors like color, design, location relative to urban centers, or nearby vegetation may have some aesthetic or environmental impacts but do not directly enhance the physical ability of a noise barrier to reduce sound transmission like height and structural continuity do. Thus, focusing on the dimensions and unbroken nature of the barrier itself is essential to maximizing its noise-reduction capabilities.