Does this busker have what it takes to make it in the opera world?

It takes a certain musical talent to stop Thomas Jones dead in his tracks when he’s walking down the street. In his 26 years teaching voice and vocal performance practice through the Office for the Arts and Holden Choirs at Harvard University, he’s listened to, and walked past, his fair share of buskers.

But last month, when Jones heard Marshall Ames Richards, a 30-year-old lyric tenor who was showcasing his voice outside of the Boston Public Library, he felt compelled to introduce himself.

“At first, I listened to him and said to myself, ‘What in the world is he doing out here?,’” said Jones. “And then I listened longer and said, ‘This is a real natural ability.’”

Jones, who has been meeting with Richards to help him perfect his talent for future auditions, isn’t the only person who has taken notice. The Alabama native has become something of an online sensation, as passersby take videos and photos of Richards and share them on social media, using the hashtag “Boston Opera Guy.” (There is a second singer known unofficially as “Opera Guy” in Boston, but the two are friendly, and Richards cleared the name with him, he said).

Richards has also been tapped by the Friends of the Public Garden, the organization that helps maintain the Public Garden and Boston Common, to perform once a week at Brewer Fountain Plaza following the group’s “Piano in the Park” series.

Musically, a lot has happened for Richards since he moved to Providence from New Orleans five months ago and began performing in Boston.

“This is a world-class city for classical music, and I want to be as much a part of it as I can be,” said Richards on a blistering hot afternoon, as he took a break between songs outside the Boston Public Library, one of his favorite spots.

“It’s a beautiful city. I love everything about it,” he said.

Richards, who sports a grizzly beard and long hair that he ties into a ponytail, has been a musician, in some form, for most of his life.

Growing up, he played bass, drums, saxophone, and guitar and explored the worlds of ska, funk, and rock. He began his foray into the complicated world of classical music and opera around the age of 18, following a stint as a singer in a heavy metal band. Richards wanted to expand his musical palette.

“I started taking some [singing] lessons from a teacher in Mobile, Ala., and he introduced me to some Mozart and some Handel, and right away when I heard it, I said, ‘This is the greatest music,’” said Richards, who had dabbled in classical as a kid. “There’s no better music on the planet.”

A graduate of the University of South Alabama, Richards had been living in New Orleans for the last three years where, as in Boston, he was known as the “Opera Guy,” working as a busker full time.

Richards’s voice comes through a small, black amplifier that’s hitched to a rolling cart. The speaker gives off a slight crackling sound similar to an old record spinning on a turntable. It adds, even if unintentionally, a certain quality to his voice that transports the listener to an earlier time.

When Richards sings, he, too, seems to go somewhere else entirely. At times, he stares down toward the ground or closes his eyes. Or he reads music from the iPhone and tablet that rest on a little ledge on his microphone stand. His eyebrows rise and fall with the notes like waves lapping against the shore of some remote Italian beach.

His voice is so crisp and unexpected, several people who passed by Richards in Copley Square last week asked whether he was lip-synching to a CD.

“I get that all the time,” he said, brushing it off.

But when people realized his voice was authentic, most were in awe. A group of children in matching fluorescent yellow shirts, who appeared to be with a day camp, clapped and cheered as they strolled down the steps of the library and off toward St. James Avenue.

Visitors hanging out of the windows of a trolley tour bus craned their necks to watch his performance as they idled at a red light. Two men argued playfully about whether he was actually singing. Nearly everyone in a small crowd that gathered had their smartphone cameras aimed at Richards.

A woman who was buying a slush from a stand across the street couldn’t believe her ears. She trotted across Dartmouth Street, toward the sound of the music, and nearly cried as she stood several feet from Richards.

“I thought, ‘This can’t be a real person!’” said Diana Sabella. “This music, it’s like, I want to go to Italy tomorrow. He’s really moving me. His voice is amazing.”

Richards plans to continue taking lessons with Jones, the vocal coach — his Baroque style needs some development, he admits — so he can prepare for auditions in the fall with some of Boston’s notable musical establishments, such as the Boston Lyric Opera.

Until then, he will keep bellowing “Ave Maria,” and “O sole mio” for the public to enjoy.

“I just wouldn’t do anything else,” he said. “I’ve already made up my mind that this is what I’m going to do for the rest of my life — it doesn’t matter if I have to do it on the street. If the doors don’t open, I’ll break through a wall.”