What this means for learners
Lue and Thai share 35 sounds — roughly 74% of Thai's inventory overlaps with Lue. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 12 sounds found only in Thai represent the greatest pronunciation challenge for Lue speakers. The adult brain tends to map unfamiliar sounds onto the closest native equivalent — a process that produces the characteristic "accent" of a second-language speaker. Learning to hear and produce these sounds as distinct requires focused ear training, not just repetition.
Conversely, Lue has 4 sounds not used in Thai. Native Thai speakers learning Lue will face the mirror-image challenge with these sounds.
Phoneme inventories from PHOIBLE. Data reflects one documented inventory per language; some variation exists across dialects and sources.