There was an article in this week's Time Magazine about a (relatively) new sound engineering software tool that's rapidly becoming a widespread staple of sound recording engineers throughout the music industry. The program is called Auto-Tune, and it's used to adjust the pitch of singers so that their voice is in tune with the note closest to the one they're trying to hit. The program is used to turn wavering or mediocre vocal performances into pitch perfect ones, and it's the reason that you're now hearing some fairly mediocre pop singers suddenly turning out songs that are pretty near perfect, at least from a pitch/tuning standpoint. One idiosyncrasy of the program is that the user can adjust the amount of time that it takes for the original pitch to bend in order to reach the target pitch (in essence, how quickly the missed note bends to hit the target pitch). A bunch of "let's all be different together" type sound engineers have repeatedly used this effect to create the sort of sci-fi, robotic, singing-through-a-fan style vocals that first appeared on Cher's 1998 song, "Believe", but which have also been used on a number of other songs ranging in style from R&B to hip hop to pop rock (note: this noticeably robotic sort of sound is a side effect of the program's use, and does not appear on the vast majority of recordings that use the program- most of the time the only sign that the program has been used is perfect singing as created by non perfect singers).
Auto-Tune definitely has legitimate uses. If someone records a near perfect version of a song, but hits a couple of wrong notes, Auto-Tune can be used to fix the mistakes without having to re-record the entire track. Auto-Tune can also be used in order to help vocals remain consistent throughout a song, which allows for easier "click and paste" editing through Pro-Tools (this sort of editing has its own issues in terms of creating music that musicians may or may not be able to reproduce live, but it's well-entrenched as the industry standard).
Nonetheless, there are some issues with Auto-Tune that ought to be considered in terms of the impact that the software has upon music as an art form. Starting with this: so now you really don't even need to be able to sing in order to be a singer. This is swinging the door wide open for a whole new generation of Britney Spears style performers who really can't carry a tune (most of these pop stars already don't play instruments or write any of their own music), but who have a marketable look and a carefully crafted "style" which is designed to sell records. Apple is currently working on an auto-tune application for their iPhones which will allow users to make perfect recordings of their own voice to share with friends. Home computer versions of auto Tune are available for less than $100 for use in home studios. If they had possessed Auto-Tune at the time, the guys in Milli Vanilli probably wouldn't have needed to lip synch because the engineers in the studio could have just altered their real voices enough to make them palatable to a pop audience. As the article points out, Auto Tune makes it possible for someone like Kanye West to sing while making it sound like he never misses notes (don't get me wrong- Mr. West has got some skills, but perfect singing just isn't one of them). Auto-Tune may also be making some fairly decent singers much lazier, as they know that sub standard performances can just be "run through the box" and fixed through engineering. Some of the blood, sweat and tears involved in making a perfect recording (as well as some of the passion and emotion) may be lost when performers know that the computer can always clean up their mistakes.
Another point, this one probably a more troubling one, is discussed by superproducer Rick Rubin in the article. Rubin argues that Auto-Tune robs singers of a great deal of the uniqueness, individuality, and emotion that comes through in their voices. Aside from the obvious examples of "unique" sounding singers whose voices would probably be all but ruined by bending them to make them consistently in tune (Bob Dylan, Tom Waits, etc.), even singers more well-known for their technical accuracy occasionally sing off-pitch notes, but this adds to the emotional uniqueness of their performance (the article cites some notes in Norah Jones's album recording of "Don't Know Why" as an example).
Auto-Tune puts people in tune, but it robs performances of some of their emotion and personality. Auto-Tune produces technical accuracy, but at the risk of making singers sound like very pretty robots. Recordings with Auto-Tune may sound technically perfect, but lack the emotional impact of an original, unmodified recording of natural human performance.
Anyway, I'm by no means a music professional, but I'm still somewhat sensitive to all of this monkeying around with sound waves in the interest of making music sound "more perfect". The guys in my own band, Mono Ensemble, are generally into making music with a minimal number of effects put on the music between the time it leaves out mouths or our instruments and the time people hear it. We use some distortion on our guitars, but we use very little (if any) reverb, chorus, etc. I'm not sure that this sort of performing technique has been a really conscious decision (every once in a while someone will make a foray into some kind of crazy effects, but it usually doesn't last very log), so much as it's been a product of just wanting people to really here what we sound like (i.e., if people are going to like or dislike our music, we just kind of want it to be because of the songwriting or performance- not because they like or dislike some effect we're using). Of course, we also don't use a lot of effects because we're usually doing things on the cheap, and effects generally cost money.
Anyway, Auto-Tune probably has its place, and eventually producers and engineers will settle down and quit using it on everything they create, but the most important thing, in the interest of simply preserving a little musical integrity, is just to make audiences aware of the fact that so long as producers are pushing the use of Auto-Tune, what people are hearing on recordings is not necessarily what they're favorite singer actually sounds like. Singers who forego use of the Auto-Tune probably deserve a little extra credit, and when people hear a note that sounds out of place, nowadays audiences probably ought to realize that even mistakes are a choice, and listeners ought to enjoy the music for what it is- enjoying the emotion that flows through it, imperfections and all.