Code-switching

Code-switching means shifting between languages in the middle of speaking. It happens both when someone drops an English word into a Korean sentence, like saying "this is really amazing" partway through, and when someone says one sentence in Korean and the next in English. For people who regularly use two languages together, this is a completely natural speech habit.

For AI models, code-switching is a tough challenge. Models that transcribe speech into text, or read text aloud as speech, often struggle to handle pronunciation and intonation smoothly when the language changes mid-sentence. A common example is an English name or brand name embedded in a Korean sentence getting flattened into Korean-style pronunciation. A model that handles code-switching well, by contrast, recognizes the point where the language shifts and continues naturally with the pronunciation and intonation appropriate to each language.

That's why code-switching performance has become a benchmark when evaluating voice AI or chatbots aimed at regions with many multilingual speakers. Whether a system can understand mixed-language speech and respond naturally in kind is what separates real-world usability from the rest.

Try giving a chatbot or voice AI a prompt like "introduce yourself using a mix of Korean and English within a single sentence." Check whether it moves between the two languages smoothly, without awkward breaks, and keeps pronunciation and grammar appropriate to each language — that will give you a sense of how well it handles code-switching.