Phonetics – the study of the sounds that form human language – can be divided into two categories. The first type of phonetics, articulatory phonetics, examines the speech organs and processes by which humans produce sounds; the focus is on the speaker of language. The second type of phonetics, acoustic phonetics, focuses on the sound that is produced when a person speaks; the aim of acoustic phonetics is to understand the acoustic properties of speech, and how that speech is perceived by the listener’s ears.
The first type of phonetics, articulatory phonetics, examines the sounds of human language at the source of their production. It looks at how a person forms his words. Particular parts of the human body, referred to as “organs of speech,” are used to articulate words. The organs of speech include the voice box, the lungs, the oral cavity, the nasal cavity, the pharyngeal cavity, the tongue, the teeth, the glottis, the lips and the inner surfaces of the mouth. The airflow needed to produce sound comes from the lungs, and is passed through the mouth and or nose, with the glottis, tongue, and teeth being used to alter the airflow to create different sounds.
Place of Articulation and Voicing
In articulatory phonetics, linguists look at the place of articulation of various sounds; the place of articulation refers to where the expelled air blocked, thus creating particular sounds. For example, the teeth are a place of articulation; when a person places his tongue against his teeth to make a particular consonant sound, this is referred to as a “dental stop.” Articulatory phonetics also refers to voicing; sounds that do not use the vocal chords are voiceless, while sounds that use the vocal chords are voiced. For example, when a person forms a “t,” he is not using his vocal chords, so this is referred to as a “voiceless dental stop.” But when he uses his vocal chords to make noise while forming a “d,” this is called a “voiced dental stop.”
While articulatory phonetics focuses on the speech organs used to produce the sounds of human language, acoustic phonetics focuses on the sound properties of human speech. Acoustic phonetics also looks at audio perception of speech, examining how different sounds are perceived by listeners. In the study of acoustic phonetics, a phonetician looks at the frequency that a sound produces, the amplitude spectrum of the sound, and the duration of the sound. These factors are used to describe the sound acoustically.
Most linguistics use the International Phonetic Alphabet to represent all the sounds of human language. The IPA has a particular written symbol to represent every sound, and every variation of sound, that occurs in languages across the globe. The IPA is a useful tool for linguists and students of language, because a linguist who knows the IPA can read the transcription of any language and be able to reproduce the words correctly, even if they are from a language he has never learned or heard before.