What this means for learners
Thai and Telefol share 24 sounds — roughly 51% of Telefol's inventory overlaps with Thai. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 3 sounds found only in Telefol represent the greatest pronunciation challenge for Thai 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, Thai has 23 sounds not used in Telefol. Native Telefol speakers learning Thai 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.