The Grammy-winning British crooner underwent surgery last week to repair bleeding in his vocal cords that stemmed from a hemmorage. The trouabdour’s troubles caused him to start canceling shows back in April — and when he returns to the stage in July, audiences will notice.

“His voice will definitely change,” says Dr. Michelle Yagoda, an otalaryngologist at Lenox Hill Hospital and the medical director of the Brooklyn Youth Chorus Academy.

Vocal cords vibrate against each other in the throat to produce sound. When an injured blood vessel bursts into the vocal cords, it causes a bruise just like anywhere else on the body. This is known as a vocal cord hemorrhage.

Like other bruises, such hemorrhages mostly heal on their own. But some hemorrhages are large — large enough in this case that it may prevent Smith’s vocal cords from vibrating against each other in the same heavenly way.

Smith will have to lay off singing — and speaking — for three weeks post-op to give his voice adequate time to recoup. That may seem extreme, but it’s par for the course, Yagoda says.

“It’s a raw area that needs to heal,” she says. “Just like if you had surgery on your ankle, you wouldn’t be able to walk on it right away.”

She speculates Smith’s grueling profession, which requires him to strain night after night, is to blame.

“It’s like playing the World Series nonstop,” she says.

And it’s even riskier for someone with his talent.

“He goes extremely high, almost like he’s crying, and that is a very difficult technical maneuver (that can make someone) prone to injury,” Yagoda says.

But the injury could have also just been an unfortunate fluke. Hemorrhages don’t always happen because someone’s singing the wrong way.

“You could scream at a party or bar and have it happen randomly,” says Justin Stoney, the founder of New York Vocal Coaching. “You could have an allergy or cough and have it happen randomly.”

Smith’s recent weight loss — dropping an alleged 14 pounds in 14 days, and more since — could also have triggered the injury, due to his body’s “changing chemistry,” Stoney added.

Vocal problems are a risk for anyone signing up for a life in showbiz. Adele, John Mayer, Keith Urban and a slew of other stars have had surgery on their vocal cords, but all have come back swinging — and singing.

It wasn’t the same for Julie Andrews, who lost her magic touch after a 1997 voice surgery went horribly wrong.

Injuries aren’t always career-ending though. Rockers like Bob Dylan and Steven Tyler have made their fortune relying on raspy voices — which, Stone and Yagoda say, are essentially damaged vocal cords.

“You can damage your voice and use it to your advantage, then that becomes (your) sound,” Stoney says.

In the past, rockers would undergo their reparative surgeries in secret so that the industry — and fans — wouldn’t balk.

“People were afraid if their fans knew they had weakness they would not be booked and people would be afraid to take them on as a (client),” Yagoda says.

Time will tell how Smith sounds in the coming weeks, but the tenor, for one, is confident. Writing on Instagram pre-surgery, he told his fans, “In 8 weeks time I’m gonna be able to sing like never before.”

That’s true — since his voice will undoubtedly change, Yagoda says. He’ll also be able to hit notes a little clearer.

But he needs to be good to his moneymaker if he wants longevity.

“If he uses his voice properly after surgery it can increase (its) staying power,” she says.