How to Pronounce Nguyen: the Definitive Guide for Native English Speakers
English speakers struggle with Nguyen because of phonotactic constraints, the subconscious rules governing which sound combinations can appear at specific places in a word. In English, the nasal consonant produced by pressing the back of the tongue against the soft palate (the velar nasal, transcribed in the International Phonetic Alphabet as /ŋ/) exists in abundance. You say it at the end of running, song, and bang, or in the middle of finger. English phonotactics, however, strictly forbid /ŋ/ from occupying the initial position of a syllable.
When an English speaker looks at "Nguyen," the brain tries to split the initial cluster into two separate letters: an /n/ sound followed by a hard /g/. The result is usually "En-goo-yen" or "Noo-gwen." Vietnamese orthography, developed by Portuguese and French Jesuit missionaries in the 17th century using the Latin alphabet (Quốc Ngữ), uses the digraph "ng" to represent a single, unified velar nasal sound. When positioned before the rounded glide "u," the back of the mouth seals just as it does when sustaining the hum of sing, releasing smoothly into a vowel without any hard "g" click.