What makes HF scatter signals often sound distorted?

Scatter propagation occurs when radio waves bounce off irregular, uneven patches in the ionosphere rather than reflecting cleanly. This causes the signal energy to break apart and scatter in multiple directions. Because the scattered energy takes several different paths to reach the receiving station, the signal waves travel slightly different distances. This multipath effect means they arrive at slightly different times and phase relationships, causing them to interfere with one another. It is this multipath interference that creates the characteristic fluttery, wavering, and distorted sound of HF scatter signals. Distractors suggesting ground wave absorption or a missing E region do not explain this audio distortion.