Nashville, Tenn. (AP) A biographer for country music superstar Eddy Arnold says the singer has died at the age of 89.

Belmont university professor Don Cusic says Arnold died at a care facility near Nashville Thursday morning. Arnold was just days short of his 90th birthday.

Arnold's mellow baritone on songs like “Make The World Go Away,” a crossover hit on the pop charts in 1965, made him one of the most successful country singers in history.

He became a pioneer of “The Nashville Sound,” also called “Countrypolitan,” a mixture of country and pop styles.

He was elected to the country music hall of fame in 1966. The following year he was the first person to receive the Entertainer of the Year award from the Country Music Association.