Phonology is the study of sounds and speech patterns in language. The root "phone" in phonology relates to sounds and originates from the Greek word phonema which means sound. Phonology seeks to discern the sounds made in all human languages. The identification of universal and non-universal qualities of sounds is a crucial component in phonology as all languages use syllables and forms of vowels and consonants.
Syllables are involved in the timing of spoken language since speaking each word takes a portion of time. Syllables are units of measurement in language. Vowels allow air to escape from the mouth and nose unblocked, while consonants create more covering of the vocal tract by the tongue. The heard friction that is a consonant is made from the air that cannot escape as the mouth utters the consonant.
Phonemes are units of sound in a language that convey meaning. For example, changing a syllable in a word will change its meaning, such as changing the "a" in "mad" to an "o" to produce "mod". A phoneme can also achieve no meaning by creating non-existent words such as by changing the "m" in "mad" or "mod" to a "j" to produce "jad" or "jod". Phonemes differ from morphemes and graphemes. A morpheme refers to main grammar units, while a grapheme is the main unit of written language.
Ensuring that the proper pronunciation is used in a language is a practical application of phonology. For example, phonology uses symbols to differentiate the sounds of a particular vowel. The vowels are classified into "front", "central", and "back" depending on the positioning of the jaw and tongue when the vowel sounds are made. Phonology also notes lip position such as if the lips are spread out or rounded as well as if the vowel sound is long or short.
The symbol for the vowel sound in words such as "chilly" or "tin" in phonology is /i/ and refers to a front, short vowel spoken with a tongue in high position and spread lips. Contrastingly, the symbol for the vowel sound in words such as "moon" or "blue" in phonology is /u:/ and refers to a back, long vowel spoken with a tongue in high position still, but with rounded lips.