ACOUSTIC PHONETICS
Acoustic phonetics is a technical area of linguistics. Phoneticians depict and analyze sound waves using machines and computer programs. Acoustic phonetics can be defined as the study of sound waves made by the human vocal organs for communication. Speech sounds, like sounds in general, are transmitted through the air as small, rapid variations in air pressure that spread in longitudinal waves from the speaker's mouth and can be heard, recorded, visualized, and measured.
Differences between individual speech sounds are directly reflected as differences in either one or several or all such parameters as duration, pitch, loudness and quality of the belonging speech waves. Basically, acoustic phonetics deals with the study and description of three topics: (a) the acoustical properties of individual phonemes (i.e., speech sounds), (b) prosody, and (c) voice quality. It forms not only the immediate link between speech production (i.e., Articulatory Phonetics) and speech perception (i.e., Auditory Phonetics), but is also important for applications in the fields of signal processing and speech technology. As such, acoustic phonetics goes hand in hand with an almost new branch of phonetics called experimental phonetics. Experimental phonetics also lends support to articulatory phonetics discussed in the following chapters.
In some ways experimental phonetics, unlike experimental work in other areas of linguistics, is like experimental work in the physical sciences. For example, we can (a) examine in detail the acoustic waveform of the sounds of speech (i.e., acoustic phonetics) or (b) can examine the behavior of the musculature during articulation (i.e., articulatory phonetics). The data collected in such experiments reflect what actually happens when a speaker speaks, and are thus called real world data.
As you have already noticed, phonetics is interested in discovering what the speaker actually does when he speaks, not what he feels or thinks about speech. Of course, people do have feelings about speech and it is important for linguistics to understand the mental, as well as the physical aspects of speaking. It has already been mentioned in chapter one that the study of the underlying mental processes involved in speaking is treated in linguistics for the most part under the heading "phonology." Phonetics studies what people actually do when they speak. Of course, the relatively new area of Cognitive Phonetics tries to characterize some of the mental aspects of speaking which are not truly phonological. Cognitive phonetics has made the boundary between phonology and phonetics somewhat fuzzy.
