Embouchure is word that has at least two meanings with regard to the flute and other wind instruments. One meaning has to do with the flute itself, mainly how the blowing hole (embouchure hole) is constructed. For example, the shape of the embouchure hole (round, oval or ellipsoidal, rounded rectangular, etc.), the chimney depth, and how the blowing edge, sidewalls and backwall are cut are the physical characteristcs. The other relevant meaning of the word has to do with the way the player holds her mouth (lips, tongue, etc.) and controls the breath in order to blow a note on the flute. Much has been written about both subjects, and as we have seen, players often have strong opinions about both topics.
I don’t intend to proceed to another “how to” topic, but, instead, I want to digress to a commercial post about the embouchure hole history of my pvc simple-system flutes. I should say that Jem Hammond in Wales is also helping me on the R & D with this, but in the meantime I am introducing a larger oval embouchure hole for my flutes. I will feel free to modify this when future R & D and player comments become available. That being said, here is the link to my website page where I discuss my recent changes.
http://dougsflutes.googlepages.com/fluteembouchure