Phonology studies how sounds function systematically within a language, focusing on the abstract units called phonemes. A phoneme is a contrastive sound unit — swapping one phoneme for another can change word meaning, as demonstrated by minimal pairs (e.g., /p/ vs /b/ in 'pat' vs 'bat'). Allophones are predictable variants of a phoneme that do not change meaning. Phonological rules describe the environments in which sound alternations occur.
Find minimal pairs in English and other languages to identify phonemes. Practice writing phonological rules using standard notation (A → B / C_D). Compare phoneme inventories across languages to appreciate cross-linguistic variation.
In articulatory phonetics, you learned how sounds are produced — where the tongue goes, whether the vocal cords vibrate, how air flows through the vocal tract. Phonology asks a different question: how do sounds *function* in a particular language's system? The same physical sound can play completely different roles in different languages, and even within one language, sounds that seem the same may be analyzed differently depending on whether they contrast meanings.
The central concept is the phoneme: an abstract mental category of sound that speakers use to distinguish words. The phoneme /p/ in English is not a single physical sound — it is a family of related sounds that English speakers treat as "the same." The /p/ in "pit" is aspirated (produced with a puff of air); the /p/ in "spit" is not. Thai, by contrast, treats aspirated and unaspirated stops as separate phonemes — swapping them changes word meaning. This means Thai has phonemes that English does not, even though both languages produce the same physical sounds. A language's phoneme inventory is a cultural and cognitive fact, not a physical one.
The members of a phoneme family — the predictable variants — are called allophones. Crucially, allophones appear in complementary distribution: each occurs in its own environment, and the environments do not overlap. English aspiration is predictable: voiceless stops are aspirated at the beginning of a stressed syllable and unaspirated elsewhere. Because the variation is fully predictable by rule, it carries no contrastive information and speakers can safely "hear through" it, perceiving both sounds as /p/. This is why native speakers of English often don't notice the aspiration difference at all — their phonological system filters it out.
The tool for discovering phoneme contrasts is the minimal pair: two words that differ in exactly one sound in the same position and have different meanings. "Bat" and "pat" form a minimal pair in English, proving that /b/ and /p/ are separate phonemes. If you cannot find minimal pairs for two sounds — if they always appear in different environments — that is evidence they may be allophones. This methodological approach is why phonological analysis is possible even for languages with no writing system: it relies only on meaning distinctions that native speakers can report.
Phonological rules describe the systematic relationships between phonemes and their allophones. A rule like "aspirate voiceless stops at the beginning of stressed syllables" captures a pattern that holds across all words in the language. These rules are unconscious — speakers follow them without knowing they exist. Discovering them is the work of phonology. The phonological grammar of a language is a structured system that maps abstract phoneme sequences onto the physical sounds speakers actually produce, and understanding that system is what separates phonology from mere transcription of sounds.