Phonetics is the study of the sounds of speech. It is concerned with the physical properties of speech sounds or signs (phones): their physiological production, acoustic properties, auditory perception, and neurophysiological status. Phonology, on the other hand, is concerned with the abstract, grammatical characterization of systems of sounds or signs.
In the case of oral languages there are three basic areas of study:
These areas are inter-connected through the common mechanism of sound, such as wavelength (pitch), amplitude, and harmonics.
[adapted from Wikipedia]
For a general coverage of the above, see See the April 5 Stanford lecture by Andrew Maas.
The Virtual Linguistics campus hosts a number of courses on Youtube, including two on phonetics.