Technology can help people sound fluent in a language, but proficiency still requires human interaction, expert says

Todd Hughes has a complicated relationship with Danish.

The 64-year-old can read a Danish novel without much trouble.

But put him in a room full of native speakers, and the plot thickens.

His Danish dilemma illustrates the difference between sounding fluent and actually becoming proficient.

Technology can help someone learn vocabulary, practice skills, or move smoothly through a translated exchange.

But proficiency is about what someone can actually do across reading, writing, listening, and speaking—and communicating proficiently still requires navigating another person.

Hughes, who trains language tutors at Rosetta Stone, knows that gap all too well.

He speaks Spanish at home with his Costa Rican husband, teaches German, grew up hearing French from his grandmother, and studies Nordic languages for fun.

He recently added Japanese to the rotation ahead of a trip to Japan.

Yet his abilities shift from one language and one skill to another.

For Hughes, fluency describes flow—how smoothly and quickly someone speaks.

Proficiency is a broader measure of ability.

It asks whether someone can understand what is being said, find the vocabulary they need, and communicate accurately when a conversation moves somewhere unexpected.

“For me, it’s a question of skill and a question of ability over a question of flow,” Hughes told Fortune .