Free variation is a phenomenon where two different sounds can be used interchangeably in speech. Linguists define this phenomenon using the test of perceived authenticity by native speakers. In other words, if the two different sounds can both be used by native speakers, and are considered correct pronunciation, their dual use qualifies as free variation.
The sounds used in free variation can be either vowels or consonants. One common example in English is the word, “data.” Here, the short "a” sound, as in “apple,” can be used in the first vowel position, or, the speaker can instead use the long "a” sound as in the word, “day.” These are commonly accepted pronunciations in American English, and most other regional forms of the language.
Other examples include the use of consonant sounds. Some of these can be extremely technical and nuanced. For example, in American English, words, like “rope,” can be pronounced either with a glottal stop, where the listener doesn’t really hear the “p” sound, or with a full plosive, where the “p” at the end is prominent.
In English, as in some other languages, examining cases of free variation can show language learners and others quite a lot about how “natural language,” or “native speech,” works. Most English learners, for example, pronounce many of the full plosives mentioned above, while many native speakers do not. A common example in American English is the use of the letter “t” in various words. For example, while newscasters or others may say the word, “Internet,” with two plosive “t” sounds, it’s also common for native American English speakers to pronounce the word more like inner-net. Some people refer to this as the difference between formal or professional American English, and “street language,” though its acceptability may also vary from one region of the country to another.
Although the term, free variation, sounds quite technical, and is mostly used within linguistic or academic communities, assessing its use is actually quite practical for anyone who is trying to imitate native speech in any language. People can use this idea to understand dialects, regional accents, or formal versus informal speech. Linguists can also use the phenomenon to study the mechanics of how people express themselves in a given tongue. The term provides a designation for when speakers may have more than one choice of pronunciation for a word or phrase, which can be a very confusing situation for language learners.