Many years ago, I was forced to perform a duty I believed to be cruel punishment and outright harassment – but that happens a lot when you have a job. I was assigned to review a sold-out Kiss arena concert, and my only consolation was that I had a seat in the press box, high above hordes of drunken, drug-crazed and apparently tone-deaf teenagers grateful for the opportunity to cover acne-cursed faces with makeup indicating which Kisser they loved the most.

From my perch, I could see what the people below could not: a strategically placed technician who, in that pre-computer era, was expertly synching tapes to accompany the band’s performances on select songs. Kiss’ then-current hit, a ballad called “Beth,” had the band backed by a string section that was faithfully re-created on tape for fidelity.

But it soon became clear from watching this silent partner work that he was also punching in vocal harmonies that might have been difficult for the vocally challenged group to replicate even were its members not spewing buckets of stage blood and attempting to remain upright on boots with 7-inch heels.

Today, such subterfuge is not required. Musical enhancements and pitch modulation for singers who wander off-key are supplied by highly trained engineers manning the sound boards. Once hired for their good ears and manual dexterity, these most valuable players are now required to serve as on-site producers who are responsible not only for achieving good sound but also for augmenting it by doubling vocals and adding additional rhythms, instruments, even orchestration. In some cases, they simply feed the original album tracks into the board, which the performer plays along to, or, in some cases, just pretends to.

Did anyone really not know that? Did even Britney’s and Justin’s most devoted fans not understand it is all but impossible to perform anything approaching a perfect vocal while at the same time executing a complex choreographed production number?

That’s the conclusion you might have reached from the fallout over the Ashlee Simpson faux pas on “Saturday Night Live” two weeks ago, when what I assume is now a former employee cued up a track Simpson had already performed, to which she responded with what the dictionary will soon define as a Howard Dean moment.

It was complicated by the rush to explain and justify – sore throat, yadda, yadda – as opposed to simply stating the obvious. Hey, everybody does it.

At one of the first stadium concerts I ever attended, a 1965 Rolling Stones show, I remember distinctly hearing an unaccounted-for piano. I learned later it was being provided by Ian Stewart, an original band member who had been demoted to road manager because he didn’t look cool, or young, enough for the image the band’s management carefully cultivated.

After the Stones were established, the late Stewart could usually be found off in a corner of the stage, sans spotlight, but acknowledged as a human being. Soon enough, groups that had a hard time duplicating their increasingly elaborate recording studio sounds on the stage dropped any subterfuge they could do it alone and brought hired hands onstage with them.

Some, however, steadfastly clung to the idea that a real band was a real band. When the Who began performing the rock opera “Tommy” in concert in 1970, its members rearranged the work for hard-rock quartet, with John Entwistle using one hand to play French horn on the overture, and the other to tap the strings of his bass.

But all the members of the Beatles would claim that the reason they abandoned live performance was because they could not hope to replicate onstage the sounds created on their post-“Rubber Soul” albums, as anyone who ever heard painful live recordings of “Paperback Writer” or “If I Needed Someone” would attest.

When the late George Harrison played his final concerts in Japan, however, he preceded “Taxman” with a tape of the muffled cough studio lead-in that had been left on “Revolver.” Paul McCartney routinely performs songs from “Sgt. Pepper” and beyond augmented by samples from the original recordings. Moreover, bands from McCartney’s to the Grateful Dead have punched up alleged live albums with vocals and other sounds re-created in the studio.

So why do acts from Milli Vanilli, which became a punch line after it was revealed that its members had little to do with their recordings, to Simpson feel compelled to maintain the subterfuge? Only because they are probably aware there is no “there” there to begin with. They are not actual performers, but marketing creations – like the Archies or Josie and the Pussycats, but in human form.

To avoid further disappointment, I suggest that all parents sit down tonight with their tweenies and tell them the truth: “Sweetheart, there really isn’t an Ashlee Simpson, but that’s not really what’s important. It’s the spirit of a sexy kid sister in low-slung jeans pretending to sing inane songs created entirely in the studio by cynical profiteers that really matters.”