thsound

The th-sound is a linguistic term used to describe the pair of interdental fricative consonants found in English and some other languages. It comprises two phonemes: the voiceless /θ/ as in think and paths, and the voiced /ð/ as in this and mother. Collectively they are commonly referred to as the “th” sounds, and they are typically written with the digraphs th or, in historical texts, with the letter thorn.

Articulation and phonetics. Both sounds are produced with the tongue blade placed between or very close to the upper and lower front teeth (interdental position). Air flows through the narrow gap, creating a friction noise. The voiceless variant /θ/ has no vocal fold vibration, while the voiced variant /ð/ involves periodic vocal fold vibration. They are considered non-sibilant fricatives and can vary slightly in articulation across dialects, sometimes aligning more with dental or labiodental touches in casual speech.

Occurrence and usage. In English, /θ/ and /ð/ contrast to distinguish words such as think versus this, thin versus then, bath versus Bav? often leading to minimal pairs that rely on the difference. The two sounds also appear in a number of other Germanic and non-Germanic languages, though their distribution and phonological behavior can differ. Orthographically, they are almost always represented by the letters th, with occasional historical or dialectal alternatives. In older English texts, the thorn letter (Þ/þ) and the eth letter (Ð/ð) were used to denote these sounds before the th digraph became standard.

History and orthography. The th-sounds historically arose within the Germanic language family and in Old English were written with the rune thorn (Þ) or eth (Ð). After the Norman Conquest, printers favored the th digraph, which gradually supplanted the special letters in modern English. Some dialects and languages retain variations or simplifications of these sounds.

Learning and variation. The th-sounds are among the most challenging English phonemes for non-native learners, often substituted with /t/ or /d/, /f/ or /v/, or omitted in casual speech. Pronunciation practice typically focuses on correct tongue position, voicing, and attention to word-internal and word-boundary contexts.