Diffraction Horn: In order for a speaker to have a large listening area, the width of the speaker must be smaller than the frequency of the sound it's emitting. You might think that it's only the size of the speaker that matters, the bigger the better, but, thanks to diffraction, the sound waves emitting from the speaker can bend around it and disperse sound all over the room. One application of a wide dispersion is the diffraction horn, a type of speaker. The width of a diffraction horn is much smaller than the wavelengths of the sounds it emits. The first diagram shows the correct mounting of a diffraction horn where the width is parallel to the floor. This allows the widest possibe listening area. The green lines mark the listening area of the speaker. In the second diagram the speaker is mounted incorrectly, and so the listening area is greatly reduced.