About Conical Horns
The conical horn is the simplest horn shape. The cross-section increases linearly, like a cheerleader's megaphone. Compared with all other horn flares, conical horns have a precisely defined radiation characteristic. There is no disruption to the wavefront as it moves out towards the horn mouth. The "horn sound" is nil with a conical horn. Because the wavefront has a smooth passage, it has perfect phase.Another advantage is that the cross-sectional area in the vicinity of the horn throat increases more rapidly than for exponential horns. This thus reduces the sound pressure in the horn as well as distortions due to the compressibility of air.
What conical horns sound like....
Since conical horns have no curvature, the ever emerging wave is not deformed as it moves from the throat to the mouth. This means that there is a linear pressure change throughout the horn.
When this condition is met, the horn will have very low 'air column' distortion, or distortion cause by squeezing the air at the throat. Conical horn also have good phase response, due to the reason stated above.
In short, the conical horn amplifies the sound, with the least disruption to the sound wave.
The sound of a conical horn system has very little trace of the "honky" sound usually associated with horn. Because the horn has good phase response it can be crossed over with another horn or direct radiator very smoothly.
Directivity is another positive feature of a conical horn. The sound goes where you want, cutting down unwanted room reverberation.
The end result of all of this is that when you hear a horn system, it has a very lifelike sound. Bells and horns sound like the real thing. Nothing comes close the sound of a cello (especially the Mercury recordings with Starker.)
If you were to clap your hands together in an auditorium, you will hear the echo more clearly- you literally hear more information. This is due to a linear wavefront and linear phase.