Idol Chatter & Voice Views

David Cook performs “Heartbeat” on American Idol. (FOX Photo)

David Cook, the Season 7 winner, performed “Heartbeat” while images of past Idols winners were shown on the big screen in the background.

The song is from David’s 2015 “Digital Vein” album, which he released independently, but which still managed to debut at number 35 on the Billboard 200 in October.

Coincidentally, in a twitter Q&A earlier in the day, David said “Heartbeat” was the most challenging song to record and sing live since it opened the album and opens lots of his shows.

“First song of the night, trying to find the pocket for the rest of the show,” he wrote in response to which of his songs is the toughest to play live.

On Idol, he need not worry. He sounded fabulous as always.

Katherine, the Season 5 runner-up, sang “Somewhere Over the Rainbow,” the song she’s probably best remembered for covering on Idol.

The “Scorpion” star decided to stand for this performance. Back in 2006, she delivered the semifinal performance sitting in the middle of the Idol stage.

Katharine also released new music last year. In fact, her album “Hysteria” hit iTunes the same day as “Digital Vein.” But it was largely ignored, despite featuring some of Katharine best music to date.

One of the best tracks is “Round My Little Finger,” a song co-written with Sia, a mentor on Thursday’s show.

Both Katharine and David are on the long list of past Idol stars expected to make an appearance at this season’s April 7 finale.

Here are the videos of their Thursday performances, followed by photos provided by FOX.

David Cook performs “Heartbeat” on American Idol. (FOX Photo)

David Cook performs “Heartbeat” on American Idol. (FOX Photo)

Katharine McPhee performs “Somewhere Over the Rainbow” on American Idol. (FOX Photo)

Katharine McPhee performs “Somewhere Over the Rainbow” on American Idol. (FOX Photo)

Katharine McPhee performs “Somewhere Over the Rainbow” on American Idol. (FOX Photo)