:laugh Wow, was that fun?

yes that's right

and about that, those things are wireless, but not like wireless that you only have the earphone thingies that's in her ear, they have wires that connect to the lil receiver box she has on her waist or just above her "rear end".

and by the way, don't know if anybody ever noticed or posted this but, did you ever notice that every outfit/costume she wears when performing, has a specially designed "pocket" for holding that receiver that matches her outfit/costume? pretty cool eh :)

^ive seen the pocket that matches..its very cute...^___^ they probably do that to make the reciever less seen

Haha, hilarious! :D

As many people have already mentioned, they are for her to hear what her band is playing aswell as to hear her own voice. The speakers on the stage are made specially for forcing the sound forward, not backward. Ayumi is more or less not hearing a bit of what her band members are playing unless she puts the headphones on. She is also one of the only people who can hear the audience cheer/scream/sing along if she takes them of, everyone else in the audience is deafened by the sound of the speakers. The cheering of the crowd is always very apparent in the DVD versions, like when she runs on stage when the Encore starts. When you are there, in the arena, you can barely hear it because of the insane sound level having put your hearing down.

I think they look amazing, I really want a pair :).

I guess no one really answered the question 'bout the backing vocals, well first the music is recorded (this way actually: drums, bass, guitar ,piano, FX, ) then the lead vocals are recorded (once the music's recorded it's easier to follow the tune listening to the instruments, that's what u hear in the studio's headphones) and then the backing vocals can be either recorded by the singer (or other singers) or made in the computer during the mix. U basically sing the chorus but at a lower octave (i dunno if u call it like that in english) or at a higher one. But u gotta be kinda well trained to do this.
In live shows u can't listen a thing of what u'r singin (in fact u don't even listen the people) the stage is very quiet (4 me, it feels like the studio, actually) so in headphones u listen to yourself, the music, and any comments that the guy in the console (sound engineer) wants to tell u (like 'hold on for the next song, the pedals of the lead guitar ain't workin').
And about Ashlee Simpson (who I don't know but I know someone who does know her) she listens herself (on the earphones) and also a vocal track 'cos she has no muscular memory (the one that makes u memorize the position of diaphragm (i dunno if it's said that way) and mouth to make a certain tune) for tones and can't find 'em just listening to the music.
I hope i've helped u, and sorry if i wrote sumthin' really long!!

^ Thanks for the explanations, very much appreciated.

I've heard of that the lead vocal can be recorded first, but I guess that is sort of rare.