One week into the 2012-13 TV season, the singing showpocalypse has gripped the nation.Two broadcast networks have flooded the prime-time landscape with performances by potential new recording artists on four nights; viewers already are suffering from an acute case of karaoke fatigue.NBC’s ‘The Voice’ airing two hours on Monday nights and one hour on Tuesdays is in the lead.Thanks to ‘The Voice’, NBC the network that was barely worth mentioning last autumn in any discussion of Monday-night ratings was the ratings leader during Premiere Week’s Monday among 18-to-49-year-old viewers.And Tuesday’s ‘The Voice’ was that night’s number one-ranked show in that age bracket, which is the currency of ad sales for entertainment programming.Both nights of ‘The Voice’ landed in Premiere Week’s top ten. And overall, ‘The Voice’ averaged 12 million viewers.‘The X Factor’ is playing catch-up. Its two editions, airing on Wednesday and Thursday nights, hovered at number 14 and 18 in the 18-to-49 age group during Premiere Week.The two ‘X Factor’ editions averaged fewer than 10 million viewers overall.Even so, Fox won Wednesday with two hours of ‘X’. And an ‘X’ repeat did better on the first Friday of the new TV season than did the season debut of JJ Abrams’s ‘Fringe’ on Fox.This ratings battle is important because advertisers pay a premium to buy time to pitch products during a show that plays like a live sporting event: Viewers watch in real time, and there’s no jumping over ad breaks and Ford music videos.That helps explain why ‘American Idol’, which airs on Fox from January through May, has been America’s most expensive prime-time show the past few seasons, according to the publication Ad Age.Last season, the cost of a 30-second spot during ‘Idol’ hit a half-million bucks, according to Ad Age, which compiles data from as many as six media-buying agencies and other sources for an annual survey of broadcast TV show ad prices.And that ad rate rose as ‘Idol’s’ competition progressed: Ad Age found that some 30-second ads in the show were going for as much as $640,000 in the show’s later weeks.Last season, ‘Idol’ gained just 11.5 percent of its overall audience from DVR viewing. That’s compared with pack leader ‘Modern Family’, which gained nearly 40 percent more viewers via DVR viewing. The 28 most DVR’d broadcast television series last season, in fact, all had one thing in common:They were scripted.One week into this TV season, ‘The Voice’ and ‘The X Factor’ are proving to be similarly DVR-resistant even though DVR-ing overall is up significantly, Premiere Week to Premiere Week. Some industry navel-gazers (who spoke on the condition of anonymity) speculated that at least part of the DVR bump might be because viewers record programmes so they can watch the heavy load of singing shows live.But that glut has led to a sort of singing-show fatigue. Both ‘The X Factor’ and ‘The Voice’ are down in the ratings compared with their most recent edition: last autumn for ‘X’ and last spring for ‘The Voice’.“These shows are becoming a commodity. Every night of the week, there’s pretty much one on,” said one of those broadcast execs who spoke on the condition of anonymity Hollywood executives being a notoriously shy group, like little fawns in the forest.“You’re going to find your singing show Monday, Tuesday, Wednesday and Thursday and in the spring, it’ll be the same thing,” the exec continued. “That ‘event’ quality ‘Idol’ used to have is clearly out the window.”So is this autumn’s singing-show showdown happening a couple of seasons too late?NBC took a calculated risk by adding an autumn edition of ‘The Voice’, knowing that the show would probably take a ratings dip but would give the network a better platform off of which to launch its new season.It’s paid off. The new ‘Revolution’, debuting after the singing show Monday, is one of Premiere Week’s big success stories. One year ago, the network’s time-slot occupant, the new ‘Playboy Club’, was the season’s first cancellation.Armed with ‘The Voice’ on two nights, NBC won Premiere Week among younger viewers for the first time in nine years.Not coincidentally, the day the Premiere Week stats came out, NBC announced that it had picked up ‘Revolution’ and ‘Go On’ as well as Tuesday’s ‘The New Normal’, which follows ‘Go On’ for the rest of the TV season.Not so clear is the picture for ‘The X Factor’, which got a reboot for its second season after its first season fell short of the 20 million viewers forecast by creator Simon Cowell. A reported $15 million was spent to hire Britney Spears, who replaced Paula Abdul at the judges’ table. And Nicole Scherzinger was replaced by firecracker Demi Lovato. Even so, the show came in 3 million viewers short of last autumn’s Premiere Week.That has to give pause among Fox suits, who’d seen a ratings uptick when they replaced the ‘Idol’ judges Kara DioGuardi, Ellen DeGeneres and Simon Cowell with Steven Tyler and Jennifer Lopez two seasons back and presumably expected a similar uptick for ‘The X Factor’ this autumn. Fox recently announced another judge-panel reboot for the next season of ‘Idol’, after last season’s ratings tumble a reboot that’s costing a reported $18 million for Mariah Carey alone. Also new to the show: Nicki Minaj and Keith Urban, who join returning judge Randy Jackson.Fox isn’t the only network keeping a close eye on the pluses and minuses of judge shuffling. NBC announced a couple of weeks ago that Shakira and Usher would fill in for regular ‘Voice’ judges Christina Aguilera and Cee Lo Green for the show’s spring edition, so Aguilera and Green can concentrate on their recording careers.It looks as though ‘X’s’ best hope of a ratings recovery is the addition of its co-hosts, Mario Lopez and Khloe Kardashian, who are expected to join the show in time for the November sweeps ratings derby when live competition episodes finally get underway.