The beaming of line source and panels 'projects' the sound at the listener, and limits the higher frequency content of the room's reverberant field that exaggerates the localization of the source, thus making a forward presentation
My guess is that it has something to do with dispersion of and room interaction with the signal from the upper-mid range thru the highs. Be nice to know though.
I beg to disagree with Duke on this one. To me the narrow or beamed presentation is a dead give away that the vocalist or piano is NOT in the room but at a distance.
Narrow or beaming speakers such as the DAL SC V or panels tend to favor classical music (at a distance) whilst wide dispersion speakers tend to favor a jazz club or rock group more intimate presentation where you feel the singer is in the room (or you are five rows back)
Of course I agree with Newbee that part of the answer is in the way the ear/brain interprets the reverberant field as being realistic or not. A second element is the way the bass needs to be dynamic for listening close up otherwise the illusion in the mid range fails when you hear the kick drum. This is a frequency/dynamic range effect that you can also hear on some bad recordings where you have the disturbing impression that the vocalist is in your room but the drummer is somewhere at the bottom of a tunnel or far away or is somewhere backstage. The third piece is reverberant energy on the recording itself from the recording venue or as deliberately mixed (more often the case today)...this gives spatial cues as to placement of instruments and vocalists and it may easily interfere with the illusion of an intimate presentation if it is not achieved in a convincing manner.
If you want a non intimate presentation try Talking Heads Stop making Sense. An intimate or forward presentation would be Eva Cassidy Live at the Blue Note or Tom Petty's "Last Dance with Mary Jane". In fact the recording plays a big part of it.
