Summary
Highlights
Unlike consonants, vowels are sounds made without closing the vocal tract, instead subtly changing the tongue's shape. English has many more vowel sounds (12-21) than vowel letters, causing potential ambiguity in pronunciation, which the IPA addresses.
Vowels are gradient, meaning there's a continuous movement between them. We can map vowels based on features like tongue height (high/close vs. low/open) and tongue backness (front vs. back). Examples include [i] (high front) and [æ] (low front).
Lip rounding is another crucial feature, with sounds like [u] being rounded and [i] being unrounded. Some languages have rounded front vowels like [y] or unrounded back vowels like [ɯ]. These three features – tongue height, tongue backness, and lip rounding – define the vowel space.
Mid vowels like [e] (mid front) and [o] (mid back rounded) fill in the vowel space. The central vowel [ə], known as schwa, is the most common vowel in English. Diphthongs are two vowels pronounced together, like [oi], formed by combining two vowel symbols.
The vowel space is represented as a trapezoid due to jaw mechanics, using rounding as a paired distinction. Languages vary greatly in their vowel inventories; English has a large number (16-20+), while languages like Spanish have around five, and others like Arabic have even fewer, often balancing with more complex consonant systems.
Diacritics add further precision to vowel description beyond primary features. Length indicates how long a vowel is produced (e.g., [i] vs. [i:]). Nasalization occurs when air flows through both the mouth and nose (e.g., in French). Tone involves changing vocal pitch to differentiate word meanings (e.g., in Mandarin), distinct from intonation in languages like English.
This episode concluded the discussion of the IPA's representation of sounds, focusing on articulatory phonetics. Future episodes will cover acoustic and perceptual phonetics, and how sounds interact in connected speech, known as phonology.