Phonology is one of the core fields that compose the discipline of linguistics, which is defined as the scientific study of language structure. One way to understand what the subject matter of phonology is, to contrast it with other fields within linguistics. A very brief explanation is that phonology is the study of sound structure in language, which is different from the study of sentence structure (syntax) or word structure (morphology), or how languages change over time (historical linguistics). A common characterization of the different between phonetics and phonology is that phonetics deals with “actual” physical sounds as they are manifested in human speech, and concentrates on acoustic waveforms, formant values, measurements of duration measured in milliseconds, of amplitude and frequency, or in the physical principles underlying the production of sounds. On the other hand, phonology is an abstract cognitive system dealing with rules in a mental grammar: principles of subcon...