Ratings: Idol Surges With Top 13 Sing-Off, NBC's Whitney and Chelsea Both Rise

American Idol cued up some unarguable gains this Wednesday, as its Top 13 sing-off drew 18.5 million total viewers and a 5.6 demo rating, up 7 and 13 percent week-to-week.

Meanwhile on NBC, opposite ABC sitcom repeats but nonetheless facing Fox’s reality juggernaut, NBC’s Whitney (4.3 mil/1.6) was up a few percentage points, hitting three-week highs, while Are You There, Chelsea? (3.7 mil/1.5) rose to four-week highs.

American Idol‘s Top 13 Cover Whitney Houston and Stevie Wonder: Who Was Your Favorite?

Elsewhere:

* Survivor, with 10.6 million total viewers and a 3.2 rating, was flat in audience but up 10 percent in the demo.

* One Tree Hill (1.5 mil/0.7) shed a few viewers, while lead out Top Model (1.4 mil/0.6) saw gains of 20 percent from its premiere.

* Happy Endings, saddled with a Modern Family repeat, dropped 25 percent to 4.53 mil/2.0). Quick, someone Kerkovitch the Nielsen people!

* A CSI repeat won the 10 o’clock hour, besting ABC News’ attempt to capitalize on the Revenge buzz and NBC’s relocated Rock Center.

What were you tuned into this Wednesday night?