Before the Rev. Martin Luther King Jr. delivered his famous "I Have a Dream" speech to hundreds of thousands of people gathered in Washington in 1963, he fine-tuned his civil rights message before a much smaller audience in North Carolina.

Reporters had covered King's 55-minute speech at a high school gymnasium in Rocky Mount on Nov. 27, 1962, but a recording wasn't known to exist until English professor Jason Miller found an aging reel-to-reel tape in a town library. Miller played it in public for the first time Tuesday at North Carolina State University.

"It is part civil rights address. It is part mass meeting. And it has the spirit of a sermon," Miller said. "And I never before heard Dr. King combine all those genres into one particular moment."

King used the phrase "I have a dream" eight times in his address to about 2,000 people at Booker T. Washington High School in Rocky Mount, eight months before electrifying the nation with the same words at the March on Washington.

He also referred to "the sons of former slaves and the sons of former slave owners," saying he dreamed they would "meet at the table of brotherhood." On the steps of the Lincoln Memorial, King changed that to "sit down together at the table of brotherhood." In both speeches, "Let Freedom Ring" served as his rallying cry.

"It's not so much the message of a man," the Rev. William Barber, president of the state chapter of the NAACP, said Tuesday. "It's the message of a movement, which is why he kept delivering it. It proves once again that the 'I have a dream' portion was not a good climax to a speech for mere applause, but an enduring call to hopeful resistance and a nonviolent challenge to injustice."

Miller discovered the recording while researching "Origins of the Dream," his book exploring similarities between King's speeches and the poetry of Langston Hughes. His ah-ha moment came when he learned through a newspaper story about a transcript of the speech in state archives. If there's a transcript, then there must be a recording, he thought.

He sent emails and made calls until he eventually heard back in the fall of 2013 from the Braswell Public Library in Rocky Mount, where staff said a box with the recording had mysteriously appeared on a desk one day. Handwriting on the box described it as a recording of King's speech, and said "please do not erase."

Before listening to the recording, Miller confirmed that the 1.5-millimeter acetate reel-to-reel tape could be played safely. He brought it to an audio expert in Philadelphia, George Blood, who set it as close to its original levels as he could. Then Blood, whose clients include the Library of Congress, digitized the tape.

It proved fortunate for King that he had practiced the dream part of his speech in Rocky Mount and later in Detroit, because it wasn't part of his typewritten speech in Washington. Historians say the singer Mahalia Jackson shouted "Tell them about the dream, Martin!" as he reached a slow point in his prepared text. King then improvised, and lit up the audience with phrases very similar to those he had delivered in that gymnasium.

Three people who were in the audience that day in 1962 listened again Tuesday as the recording was played at the university's James B. Hunt Library. Herbert Tillman, who was about 17 years old at the time, recalled how happy they were to see and hear such an inspiring leader.

"Everybody was attentive to what he had to say," Tillman said. "And the words that he brought to Rocky Mount were words of encouragement that we really needed in Rocky Mount at that time."

Barber said this newly available recording of King's earlier speech — urging blacks to focus on voting rights and peacefully but forcefully push for change — is just as inspiring today.

"Make no mistake. This kind of oratory is dangerous," Barber said, "especially for those who want to go back, especially for those who want the status quo because this kind of oratory can loose the captive and set people free to stand up and fight for their own freedom."