In conversation people produce over ten speech sounds a second. The study of speech sounds has two parts. Phonetics looks at how sounds are made and heard. Phonology looks at how each language organizes sounds into a system. This level explains both in plain words, with no special alphabet to memorize.
How speech is made
Speech starts with air pushed up from the lungs. In the throat it passes the vocal folds in the larynx. Voiced sounds are made with the vocal folds vibrating; voiceless sounds are not. Put your fingers on your throat and say "zzzz," then "ssss": you will feel a buzz only for z.
Consonants are described by where and how the air is blocked. Place of articulation is where in the mouth the airflow is narrowed or blocked: at the lips for p and b, behind the teeth for t and d, at the back of the mouth for k and g. Manner of articulation is how the airflow is blocked: completely and then released for stops like p and t, squeezed into a hiss for fricatives like f and s, or sent through the nose for nasals like m and n. Vowels are described by tongue position and lip rounding.
Phonemes: the sounds that matter
Not every difference in sound counts. A phoneme is a sound difference that can change the meaning of a word in a particular language. Linguists find phonemes with minimal pairs, words that differ in one sound only: pat and bat show that p and b are different phonemes in English.
Hold your hand in front of your mouth and say "pin," then "spin." The p in pin comes with a puff of air, called aspiration; the p in spin has almost none. English speakers hear them as one sound because the difference never separates two English words. In Hindi and Thai the same difference does separate words, so speakers of those languages hear it at once. Variants of one phoneme are called allophones. Likewise, Japanese has one sound where English has two, l and r, which is why the difference is hard for many Japanese learners to hear.
Hearing is shaped early. Studies by Janet Werker and others found that young infants can distinguish sounds from many languages, but by around their first birthday they lose ease with contrasts their own language does not use.
Rules about combinations
Languages also limit how sounds can be strung together. Phonotactics are a language's rules about which combinations of sounds are allowed. "Blick" is not an English word but could be; "bnick" could not. Polish happily starts words with clusters that English forbids, and many languages begin words with the "ng" sound, as in the Vietnamese name Nguyen, which English allows only at the end of a syllable. When words are borrowed, they are reshaped to fit: Japanese turned the English baseball word strike into sutoraiku, adding vowels to break up the consonant cluster.
Pitch, tone and stress
In English, pitch mostly signals attitude: a rising pitch can turn "You're leaving" into a question. In tone languages, the pitch of a syllable can change a word's meaning. In Mandarin Chinese, ma with a high level tone means mother, with a rising tone hemp, with a dipping tone horse and with a falling tone scold. Tone languages are common across Africa, East and Southeast Asia and parts of the Americas, and by some estimates they make up a majority of the world's languages.
Signs have their own building blocks
Sign languages have a level of organization much like phonology. Sign languages build words from a limited set of handshapes, locations and movements, much as speech uses sounds. In American Sign Language, the signs for summer, ugly and dry use the same handshape and movement and differ only in where they are made: at the forehead, the nose and the chin. They are minimal pairs, just like pat and bat.
Spelling is not sound
Finally, do not trust spelling: English "ough" is said differently in though, through, cough and tough.
Worked example: where foreign accents come from
A Spanish speaker learning English may say "espeak" for speak and "estudent" for student. It is tempting to call this careless. It is the opposite: it is the careful application of Spanish rules.
Spanish phonotactics do not allow a word to begin with s plus another consonant. Long ago Latin schola and stella became escuela and estrella. An adult saying "estudent" is doing what Spanish has done for centuries: adding a vowel to make the cluster legal.
The same logic explains other accents. A Japanese speaker who blurs light and right is hearing two English phonemes through a system that has only one. An English speaker learning Mandarin who says "horse" when meaning "mother" is treating tone as attitude, as English does, rather than as part of the word. In each case the first language acts as a filter.
Seeing accents this way matters beyond the classroom. A foreign accent is evidence that a person already commands one complete sound system and is working to master another, not a sign of low intelligence. Level 7 looks at how judgments about accents can turn into prejudice.