Articulatory phonetics is the study of the way the vocal organs are used to produce speech sounds.
Acoustic phonetics is the study of the physical properties of speech sounds.
Auditory phonetics is the study of the way people perceive speech sounds, in other words, it investigates the hearing process.
The branch of phonetics concerned with the study of the functional (linguistic) aspect of speech sounds is called phonology .
Comparative phonetics studies the correlation between the phonetic systems of two or more languages and find out the correspondences between the speech sounds of kindred languages.
Practical , or normative, phonetics studies the substance, the material form of phonetic phenomena in relation to meaning.
Theoretical phonetics is mainly concerned with the functioning of phonetic units in language.