II/ Phonology
A phonetic study tells how the sounds of a language are made and what their acoustic properties are.A phoneme is the smallest segment (unit) of sound which can distinguish two words: 
Pit - bit   /P/   /B/
Rack  - rock   /A/   /O/
A linguist must establish the inventory of the different phonemes found in the various languages.Phonology has been defined as the study of sound systems, that is the study of how speech sounds function in languages.A phonological study tells how these sounds are used to convey meaning.