Kim Bum-soo confessed to suffering from trauma.

On the September 13 broadcast of SBS's "My Little Old Boy," singer Kim Bum-soo made his first appearance as a new member cast in the show.

During the broadcast, Kim Bum-soo visited a vocal research lab to practice vocalization with vocal coaches, leaving viewers puzzled. Everyone was surprised to see Kim Bum-soo, one of South Korea's top vocalists, practicing basic vocal exercises.

He showed instability in a specific vocal range. It was revealed that after experiencing vocal issues 7 years ago that forced him to completely cancel a concert, Kim Bum-soo temporarily halted all concert activities afterward.

Even until now, he has continued to experience vocal issues. A vocal coach asked Kim Bum-soo, "Shall we try singing one of your own songs? Which one would you like to try?"

In response, Kim Bum-soo selected his track, saying, "I'll try singing 'Bogosipda' ('I Miss You') for the first time in a while." He showed a deeply nervous expression, asking, "Wait, was this song always this terrifying? Does just hearing the intro make me this tense?"

Kim Bum-soo's subsequent singing was vastly different from the skills we used to know. His voice did not come out the way he wanted, breaking the hearts of those watching.

After the song ended, Kim Bum-soo let out a sigh, eliciting sympathy. Seeing his severe vocal condition, the vocal coaches also expressed curiosity about his hospital checkup results.

Drawing attention, Kim Bum-soo revealed that hospital examinations showed no issues with his vocal cords. He then began his story, saying, "I remember that day so vividly."

On the day of his concert 7 years ago, his voice suddenly stopped coming out, prompting him to rush to the hospital. Recalling the time he had no choice but to cancel the concert, he shared, "I had gone to the hospital for a checkup just the day before. The vocalization that was clearly fine developed problems overnight. The doctor said, 'How could this happen in just a day? I don't understand. In your current state, you shouldn't perform.'"

After returning from the hospital, Kim Bum-soo arrived at the concert venue. With audience members already entering, he headed to the stage to deliver the news of the concert cancellation, describing his emotions from that vivid memory: "That walk felt terrifying, like stepping onto a cold scaffold of execution."

Reflecting on that miserable time, he added, "I just wanted to disappear." He started the first song in hopes of somehow letting the audience hear his voice. However, his voice failed to come out properly, and Kim Bum-soo ultimately hung his head as he delivered the news of the cancellation.

He bowed deeply, bidding farewell one by one to the audience members heading back home. Kim Bum-soo touched viewers by sharing, "At some point, applause started to come from the audience. Many fans told me it was okay and to cheer up, but that incident left a psychological blow on me. That event remained as trauma that has persisted until now, and ultimately, it still torments me today."

Kim Bum-soo used to enjoy the stage without any fear. However, after that day, the stage became a terrifying place, and developing stage fright even led him to take a sabbatical year.

Kim Bum-soo revealed that even after his sabbatical ended, the trauma struck him once again, making it impossible for him to produce his past voice to this day.

Expressing sympathy, the vocal coach noted, "It is something that could happen to any singer. However, I think the trauma lingered much more strongly because of the weight and burden of being a top vocalist."

Cheering him on by saying he has improved a lot and adding, "I think only about 10 percent is left now," the coach encouraged him. In response, Kim Bum-soo passionately sang "Bogosipda" once more, drawing attention by producing a much more stable voice than his previous attempt.

(Photo: Yonhap News / Produced by SBS Digital News) (Reporter: Kim Hyo-jung)