Monaural beats are the result of mixing two separate steady tones externally, producing nearly the same sound like with the binaural beats. The concept behind monaural BWE is the same with that of binaural beats.
Two slightly different steady tones are introduced to each speaker, and the resulting sound is mixed before it reaches the ear. The result is similar to a binaural beat.
As the produced tone is formed outside the skull, monaurals, like isochronic tones, do not require headphones to work.
There is also a study on monaurals that showed that are five times more effective than binaural beats. As you see in the picture, the waveform of a monaural beat has a clearer imprint than a binaural which is more shallow.
Unfortunately, I haven’t tested many monaural products to compare them with binaural beats. Though, there is some brainwave entrainment software, like Neuro Programmer 3, that contain monaural sessions.
Unmasked monoaural beats can be heard more easily than unmasked isochronic tones. Their effect in stimulating the brain is powerful and noticeable.
If binaural beats are considered to be soft-core and isochronic tones are the hardcore then, monaural beats are in the middle.\
You can check this forum for more information about brainwave entrainment. It is the community site of the Transparent Corporation which develops brainwave entrainment products.
One of these is the Neuro Programmer, which is an excellent software that also contains monaural sessions. The discussions there, are not limited just to the company’s products. You can find reliable and valuable information for many brainwave entrainment products, general discussions on the topic and more.