What is nearfield listening?

Has nothing to do with the angle formed by the speaker. Near field is simply listening close enough such that the direct sound from the speaker is more than the room reflected sound.

Onhwy61 is correct that nearfield mean where direct sound is louder than all of the reflected sound at the listening position. This distance would vary considerably, depending on the speaker, the size of the room, the reflective quality of the room, etc.

The primary drawback is that recordings are mixed, to some degree, to sound their best with "normal" speaker/room/listener arrangements. This means that there is eliance on the room providing more reflected sound in the mix than that provided by nearfield listening. I would expect that, as time goes by, more mixing would be for nearfield listening, given how much more common listening to computer monitors is becoming these days. Unless a speaker is designed for nearfield listening, there are other problems to contend with--e.g., large speakers with spaced out drivers may not have the sound of the drivers properly integrated at close distances; because high frequencies drop off more than low frequencies as distance increases, speakers are balanced for a particular distance that is probably farther away than nearfield.

The best thing about trying nearfield listening is that it is free. Just move your speakers or yourself and try it out. In a typical room, you probably don't have to get closer than say 4-5 feet to get the full effect, and one can back away some to find the best balance of the attributes of nearfield and farfield listening.

Nearfield is listening close to the speakers so that most of the sound reaches your ears directly from the speakers. Its an attempt to take room acoustics and reflected sound out of the equation, much like listening to headphones. SOme speakers are designed for nearfield listening ie to sound "best" listening nearfield. The focus may be more on flat on-axis frequency response along with detail and perhaps also dynamics to some degree. SOund artifacts that require room acoustics and reflected sound to be heard, like imaging, soundstage, and "air" are not a consideration.

I agree with Mapman. Also, nearfield monitors must have drivers close together for proper integration. Floor standing speakers with drivers mounted across the front baffle are not designed for nearfield listening although many people use this type of speaker this way due to small listening rooms. This is a good reason to select the speaker that fits your room.