Headphones come in intra-aural, supraaural, and circumaural form factors.

Evidence

The construction principle for headphones varies considerably. Small headphone elements are designed to be inserted in the ear canal or attached at its entrance. Larger headphones are either supported by the pinna (supraaural) or constructed as cup structures to cover the external ear entirely (circumaural). — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 478

Categorization

• DEFINE: Defines the three headphone construction classes (intra-aural, supraaural, circumaural) as standard technical vocabulary.
• corroborated: 2 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 478