What makes two words different from each other?
It’s obvious, they have different sounds. “Bat,” is a different word than “pat” because ‘b’ /b/ is a different sound that ‘p’ /p/. “Pin” is a different word than “pen” because ‘I’ /ɪ/ and ‘e’ /ɛ/ represent different sounds.
The sounds that change the meaning of a word are called phonemes. The exact physical sound will not be the same between two people, or even exactly the same each time a person says it, but we recognize sounds that change the meaning of words. Our perception of the sound is the result of neurological processes that take in context, the speaker’s face, and other elements that form our perception of what we hear. The strongest influence is what we expect to hear.
Of all the possible sounds a human can make, every language uses a subset. Babies go through a “babbling period” where they play with their vocal tract and make a wide range of sounds. Rapidly, they favor the sounds they hear from people around them. This vowel chart is an outline of the possible vowels, and this consonant chart is an outline of the possible consonants. I call it an “outline” because there is considerable variation for each vowel or consonant. Within a language, it is common for speakers not to notice the variations. These variations are called, allophones, and I discuss this in more detail, but we can discuss this briefly with two examples.
First off, consider the two words “pin” /pɪn/ and “spin” /spɪn/. We form “spin” by adding an ‘s’ sound to the beginning of “pin,” right?
Sort of. The two ‘p’s are not the same. If I write them more accurately, I will write them as [pʰɪn] and [spɪn]. Notice the little ‘h’ after the ”p’ in “pin.” That refers to a little puff of air, called aspiration, that is released after the ‘p’ sound. You can test this. Put your hand right in front of your mouth and say, “pin” and you will feel a puff of air. Say, “spin” and there is no puff of air after the ‘p.’ If you force a puff or air after the ‘p’ in “spin,” it will sound a bit weird, but it does not change the meaning of the word.
In Mandrin Chinese (and many other languages) /p/ and /pʰ/ are as different as /b/ and /p/ are in English. They are separate phonemes, where in English, [p] and [pʰ] are different allophones of the same phoneme, /p/.
Usually, the variations are entirely precicitibale. The anthropologist, Gregory Bateson, once said that “information is differences that make a difference.”
Part of the job of a linguist can be to identify the distinct sounds in a language. The science of doing this is called phonology. This is a matter of identifying the abstract sounds that change the meaning and the allophones of the phonemes.