Languages differ widely in vowel category counts, from two to over ten.

Evidence

The number of vowel categories varies in different languages, ranging from two to a number higher than ten, depending somewhat on the classification system used (WALS, 2014). — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 575

Categorization

• XREF: Connects to WALS (World Atlas of Language Structures) language typology research. — connects to: Vocabulary sizes differ enormously between large and small-scale societies. — Joseph Henrich, The Secret of Our Success: How Culture…, 775
• corroborated: 2 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 575