Neutralization

If a language has two sounds which are distinct in one environment (e.g. word-initially), and not distinct in another environment (e.g. word-finally, or when not stressed, or in another particular position), then the distinction between the sounds is said to be neutralized in that environment. For instance, English has distinct t and d word-initially (as proven by minial pairs, such town and down) as well as word-finally (e.g. sent and send). After /s/, however, the distinction between the two sounds is neutralized: only /t/ appears (stem vs. *sdem).

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