Plot summary
Voyager encounters a technologically advanced race called the Qomar, and renders aid after a Qomar crew suffers minor injuries from a reaction with Voyager's scanners. The Qomar are extremely arrogant and dismissive to everyone, and dislike the Doctor simply for being a holographic entity. However, once the Qomar happen to hear the Doctor singing, they are immediately enthralled by him, since they never conceived the concept of music.
When the Doctor explains how music is used and how many others on the ship can perform it naturally, the Qomar invite the Voyager crew to their home system—previously off limits to outsiders—to learn more about music. The Voyager crew discover thousands of subspace channels encrypted in many ways, and tons of traffic just above the home world. The Qomar decide to transmit the Doctor's singing planet-wide, and make him a star. This accentuates his vanity, making him unpopular with his friends on Voyager. He asks to leave so he can pursue his music career on the planet. This causes more anger, as the crew believes they need his medical skills and have grown to love him as a member of the crew.
The Doctor protests, even preparing Paris to take over his position, and severely upsetting Seven of Nine, who feels like she is being abandoned. However, the aliens replace him with an upgraded singing hologram capable of a greater vocal range. The Doctor's hopes for a new life are dashed. In the end, the Doctor realizes they simply wanted him for his singing, not who he is as a sentient entity. The Voyager crew welcome him back, as symbolized by Seven delivering him a fan letter praising his talent and personality, signed by Seven of Nine.
Credits
Adapted from Wikipedia contributors, Virtuoso (Star Trek: Voyager). Paragraphs and formatting adjusted; illustrations, reference markers, block quotations and non-story material omitted.