1. Animal communication
Various animals use vocal signals/sounds, e.g.:

2. Animal communication
A cow has fewer than 10 A chicken about 20 A dolphin A fox over 30 each sound → (how many?) messages 1 message most animals can use each sound to send a single message = Most animals can use each basic sound only once

3. Human language
Human language works differently. Each language has a stock of sound units or phonemes (which are similar in number to the basic sounds possessed by animals), e.g.: How many does English have? phonetic chart.exe 44 What about Kurdish? 35 What about Arabic? 28

4. Duality
In Human language: Each sound (e.g. /p/) → (how many?) messages zero messages Each phoneme is normally meaningless in isolation (i.e. when used alone) It becomes meaningful only when … ? it is combined with other phonemes.

5. Duality
E.g.: The phonemes /p/, /l/, /i:/ have these combinations: /pli:/ (plea) /pi:l/ (peel) /li:p/ (leap)

6. Duality
Duality is the organization of a communication system into two ‘layers’/levels of structure: a layer of sounds which combine into a second layer of larger meaningful units:
So the difference is not the number of sounds
but how the sounds are used.

7. Duality Advantage: Duality makes a communication system flexible
because unlimited number of messages can be sent with a limited number of sounds

8. Duality Unique to human language or not:
Duality is very rare in animal communication
One example is birdsong, where each note is meaningless,
but the combination of notes constitutes a meaningful melody.

9. Duality
End