The top black line in this first graph shows you the 0 degree response, i.e., the response when you're looking directly at the speaker, completely level with it. The rest of the curves show what happens when you combine radiation from different angles. Notice that the green line roughly follows the black line, and both pairs of blue and red lines are very similar. That's a hint about good directivity.
These two graphs here show the speakers' horizontal and vertical radiation.
Notice how similar they look. This means that the speaker radiates similarly vertically and horizontally, so listening to the left, right, above or below the center of the speaker will not be meaningfully different until, that is, you get to 60 degrees or so.
The main reason that the LS50s have these characteristics is because of the coaxial drivers, smooth front face and small size. There are two drivers, one designed to sit in the other.
Compare this to a conventional two driver speaker like the Harbeth Monitor 30:
https://www.audiosciencereview.com/forum/index.php?threads/harbeth-monitor-30-speaker-review.11108/
Because the drivers are spaced apart, the front face is bigger and has sharp edges and other discontinuities, you get a more uneven radiation pattern. Especially vertically, where you have little holes in the contours. This is a common issue with this type of design.
