<P> As Horton lies beaten and captured, the Kangaroo easily takes the clover, and drops it . Meanwhile, JoJo grabs the horn used to project Horton's voice, runs up the highest tower and screams "YOPP!", breaking through the sound barrier just seconds before the speck hits the oil . </P> <P> The Kangaroo's son, Rudy grabs the clover and returns it to Horton . The animals finally hear the Whos, realizing the truth about the clover, and isolate the Kangaroo for tricking them . While being praised for his integrity by his neighbors, Horton even forgives the devastated Kangaroo, and she befriends him with a makeshift umbrella for Whoville . Here, the people of Whoville and the animals of Nool gather in song and recite the chorus from "Can't Fight This Feeling". The film ends with the narrator revealing that the Jungle of Nool, or rather Earth, is just one speck, like Whoville, among numerous others, floating in outer space . </P> <Ul> <Li> Jim Carrey as Horton, an outgoing, eccentric, big - hearted, loving, sweet, and thoughtful elephant and teacher in the Jungle of Nool . Horton has no tusks, lives by himself and possesses acute hearing abilities . </Li> <Li> Steve Carell as Mayor Ned McDodd, the mayor of Whoville . He has 96 daughters, 1 son named JoJo and a wife named Sally . </Li> <Li> Carol Burnett as Sour Kangaroo, who mistrusts Horton's inquisitive nature as a threat to her legal authority over Nool . </Li> <Li> Will Arnett as Vlad Vladikoff, a scary, savage, eccentric Russian - accented vulture hired by the Sour Kangaroo to steal Horton's clover . </Li> <Li> Seth Rogen as Morton, a mouse and Horton's friend in the Jungle of Nool . </Li> <Li> Dan Fogler as The Councilman, a councilman dedicated to Whoville tradition and mistrustful of Mayor McDodd . <Ul> <Li> Fogler also voices Yummo Wickersham, leader of the Wickersham ape tribe brothers . </Li> </Ul> </Li> <Li> Isla Fisher as Dr. Mary Lou LaRue, a professor at Who U . </Li> <Li> Jonah Hill as Tommy, a bear and one of Horton's students . </Li> <Li> Amy Poehler as Sally O'Malley, Mayor McDodd's wife and mother to Jojo and her 96 daughters . </Li> <Li> Jaime Pressly as Mrs. Quilligan, a bird and Jessica's mother . </Li> <Li> Charles Osgood as The Narrator </Li> <Li> Jesse McCartney as JoJo McDodd, Mayor McDodd's quiet son . </Li> <Li> Josh Flitter as Rudy Kangaroo, Sour Kangaroo's son . </Li> <Li> Niecy Nash as Miss Yelp, Mayor McDodd's assistant . </Li> <Li> Laura Ortiz as Jessica Quilligan, a bird, Mrs. Quilligan's daughter and one of Horton's students . </Li> <Li> Joey King as Katie, a cute, but eccentric little baby yak . </Li> <Li> Bill Farmer as Willie, a bear and Tommy's dad . </Li> <Li> Heather Goldenhersh as Who Girl </Li> </Ul> <Li> Jim Carrey as Horton, an outgoing, eccentric, big - hearted, loving, sweet, and thoughtful elephant and teacher in the Jungle of Nool . Horton has no tusks, lives by himself and possesses acute hearing abilities . </Li>

Voice of katie in horton hears a who