3. Language as 'vocal'
The term 'vocal' refers to the fact that the primary medium of language is sound. and it is sound for all languages, no matter how well developed are their writing systems. Many languages exist only in spoken form. For example, babies and their parents, siblings and others may communicate with sounds and gestures without knowing how to communicate in writing.
The followings are seven of features described in what ways these features are uniquely parts of human language and unlikely to be found in the communication system of other creatures.
1. Arbitrariness
2. Displacement
3. Discreteness
4. Duality
5. Productivity
6. Interchangeability
7. Cultural transmission