The 29-year-old, who plays Mike Chang on the Fox series, confessed that he has been taking vocal lessons in order to improve his singing.
"I'm not the best singer but I'm definitely not the worst," Shum told Access Hollywood. "I'm somewhere in between but I'll let the audience gauge on how good that is and hopefully the show allows me to sing a real song."
Shum went on to address the recent reports that certain cast members will be leaving at the end of the upcoming season of Glee.
"I think we'll find out very, very soon but I think the main focus, instead of what's happening on season four, should be season three," he said.
In April, Shum revealed that he is proud of his romance storyline on Glee, admitting that he hopes his character's relationship with Tina (Jenna Ushkowitz) stays strong.
Glee returns for its third season on September 20 on Fox.