The distinction between emic and etic was first proposed in the mid-1950s by the linguist Kenneth Pike. The term 'emic' derives from phonemics, which studies the sound system of a particular language that is meaningful for native speakers. The term 'etic', conversely, derives from phonetics, which studies the physical properties of speech sounds independently of the speaker's perception. The following examples illustrate this distinction. To most English-speaking people, the p sounds of pike and spike probably sound the same, but phonetically speaking, they are actually different because the former is 'aspirated' whereas the latter is 'unaspirated'. Such differences are, however, irrelevant in terms of meaning production, and are therefore ordinarily ignored by native speakers. By contrast, the p sound of pike is immediately understood as different from the b sound of bike because, even though they are articulated in almost the same way, the subtle distinction between 'voiceless' and 'voiced' that separates the two sounds produces decisive differences in meaning. Technically symbolised as /p/ and /b/, they form parts of the phonemic system of the English language. Simply put, phonetic differences are revealed when measured precisely by some sort of objective methods and standards, but seldom come to the attention of speakers themselves, whereas phonemic differences are not only perceived to be real, but also essential in their speech behaviour.