Aaryn Gries' novelty may be wearing off for viewers of CBS' "Big Brother."

The reality show's ratings dropped 13% from last week. Wednesday night's telecast scored a 2.0 rating in the key 18-49 demographic, according to preliminary numbers from Nielsen. 

Gries has generated controversy and ratings for the show with her derogatory remarks about African American, Asian American and gay houseguests. Some 6.11 million viewers tuned in for Gries' stint as "head of household," which made her exempt from eviction. 

Meanwhile, "America's Got Talent" on NBC won Wednesday night as four contestants moved on to the semifinals. It earned a 2.3 rating in the 18-49 category, down 4% from last week, for the series' season low. About 9.97 million people watched. 

PHOTOS: Cable versus broadcast ratings

Fox's "MasterChef," the cooking contest with Gordon Ramsay, came in second in the ratings. The show also slipped 4% to a 2.2 in the 18-49 demographic. The show drew 5.41 million viewers. 

NBC followed "Talent" with Australian comedy import "Camp," which increased 20% to a 1.2. 

NBC was the most watched and highest-rated network with average viewership of 6.91 million and a key demographic rating of 1.7. 

ABC's news magazine "The Lookout" was flat with last week in the 18-49 slot. 

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ryan.faughnder@latimes.com