If articulatory phonetics studies the way in which speech sounds are produced, auditory phonetics focuses on the perception of sounds or the way in which sounds are heard and interpreted. Thus, we may say that while articulatory phonetics is mainly concerned with the speaker, auditory phonetics deals with the other important participant in verbal communication, the listener.
It is again, obviously, a field of linguistic study
which has to rely heavily on biology and more specifically on anatomy and physiology.
In auditory phonetics, we are dealing with two distinct operations which are closely interrelated and influence each other: on the one hand we can talk about audition proper, that is the perception of sounds by our auditory apparatus and the transforming of the information into a neural sign and its sending to the brain and, on the other hand, we can talk about the analysis of this information by the brain which eventually leads to the decoding of the message, the understanding of the verbal message.
As a beginner however, it will be sufficient for you to get a basic idea of how our auditory system and the general hearing process work. Have a close look at the picture below, then read through the brief description that follows.
Source of the picture: jefferson.edu
Keeping it very simple, we can state, that any sound coming from any source, be it a door slamming or someone speaking to you, is spreading from that source as a sound wave, causing the molecules on its way to crowd together and move apart again or in other words, to vibrate. When these vibrating air molecules reach your ear, they cause the eardrum in your middle ear to vibrate, too and this vibration is then carried on from the eardrum to the three little bones: mallet, incus and stirrup.
From the stirrup, the vibration is carried on to the inner ear, and into the cochlea, a little coil-like organ filled with liquid. Inside the cochlea there are two membranes: the vestibular membrane and the basilar membrane. It is the latter that plays a central role in the act of audition, because this is, where the auditory receptor cells are located.
Depending on the frequency of the sound coming in, a different part with different receptor cells of the basilar membrane is stimulated. Thus, low-frequency (grave) sounds will make the membrane vibrate at the less stiff (upper) end, while high-frequency (acute) sounds will cause the lower and stiffer end of the membrane to vibrate. The cells on the basilar membrane convert these vibrations into neural signals that are transmitted via the auditory nerves to the central receptor and controller of the entire process, the brain, where we identify the incoming sound as actual sound with a specific pitch.
You can now move on to do some exercises within the field of auditory phonetics, or you can click on the "read more" button, in case you want a detailed description of how the human hearing process works.