phonetics

Phonetics is the branch of linguistics that studies the physical properties of human speech sounds. It examines how sounds are produced by the vocal apparatus (articulatory phonetics), how they are transmitted through the air as acoustic signals (acoustic phonetics), and how they are perceived by the ear and brain (auditory phonetics). Phonetics differs from phonology, which focuses on how sounds function within a particular language system.

Phonetic data are often transcribed with the International Phonetic Alphabet (IPA). Transcriptions can be broad, representing distinct phonemes, or narrow, capturing allophonic variation and diacritics. Central concepts include phones, phonemes, and allophones, as well as voicing, place and manner of articulation, and features such as vowel height, backness, and rounding.

Researchers employ methods such as spectrographic analysis, high-speed imaging, ultrasound, palatography, and electromagnetic articulography to study articulation and acoustics. The IPA provides a standard notation for describing sounds across languages, enabling cross-linguistic comparison and documentation.

History and applications: The modern study of phonetics developed in the late 19th and early 20th centuries with the work of Paul Passy and the International Phonetic Association. Today, phonetics informs language teaching, speech therapy and clinical diagnostics, forensic linguistics, and speech recognition and synthesis. It also supports field linguistics in documenting endangered languages and broad cross-language sound inventories.

Subfields include articulatory phonetics, acoustic phonetics, and auditory phonetics. Phonetics also overlaps with prosody when describing the acoustic properties of rhythm, intonation, and stress as physical signals rather than as purely grammatical rules.