What this means for learners
Totonac and Lak share 14 sounds — roughly 20% of Lak's inventory overlaps with Totonac. Shared sounds are ones a speaker already knows from their native language and will generally produce and perceive accurately without explicit training.
The 55 sounds found only in Lak represent the greatest pronunciation challenge for Totonac 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, Totonac has 12 sounds not used in Lak. Native Lak speakers learning Totonac 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.