NEW YORK - Tony Bennett has been diagnosed with Alzheimer's disease but it hasn't quieted his legendary voice.The singer's wife and son reveal in the latest edition of AARP The Magazine that Bennett was first diagnosed with the irreversible neurological disorder in 2016. The magazine says he endures "increasingly rarer moments of clarity and awareness."Still, he continues to rehearse and twice a week goes through his 90-minute set with his longtime pianist, Lee Musiker. The magazine says he sings with perfect pitch and apparent ease.A beloved interpreter of American standards, Bennett's chart-topping career spans seven decades. "He's not the old Tony anymore," his wife, Susan, told the magazine. "But when he sings, he's the old Tony."Bennett, 94, gained his first pop success in the early 1950s and enjoyed a career revival in the 1990s and became popular with younger audiences in part because of an appearance on "MTV Unplugged." He continued recording and touring constantly, and his 2014 collaboration with Lady Gaga, "Tony Bennett & Lady Gaga: Cheek to Cheek," debuted at No. 1 on the Billboard charts.