Narrowing a horn’s coverage angle concentrates energy and raises its on-axis sensitivity.

Evidence

Table 7.6 shows the results of doing this. Note that the 40° × 20° horn has a higher sensitivity, because it is concentrating the sound into a smaller solid angle. Note that the level is now much more uniform-to about halfway down the audience, the maximum variation is 4.5 dB, or ± 2.25 dB. However, the rear row at 30 m is still 14.5 dB lower than the level at 5.4 m, and this is still too much variation. One might be able to do better by using three horn loudspeakers, but this is getting more complicated and expensive. The main problem seems to be that the levels in the audience covered by the 40° × 20° horn are lower than those in the area covered by the other horn. So as a more economical solution, let’s try raising the power fed to the 40° × 20° horn to 2. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2534

Categorization

• DEFINE: Defines sensitivity in terms of concentrating sound energy into a smaller solid angle.