Compensatory Lengthening

Compensatory lengthening refers to the lengthening of a vowel sound due to the loss of a consonant. This usually occurs in the syllable coda.  This phonology process is common in English and many other languages.

The word night provides an example of compensatory lengthening. It used to be pronounced with a velar fricative. The phonetic transcription is thus [nixt]. However, the velar fricative was later lost. To compensate for the loss of the fricative, the vowel lengthened to compensate. The word was then pronounced [ni:t]. As a result of the Grent English Vowel Shift, the pronunciation of the word night later changed to [naIt].

In non-rhotic dialects of English, words such as her and service have a long schwa. This compensates for the loss of the consonant. In words such as here and tour, however, many speakers have a schwa which replaces the rhotic consonant.

An example of compensatory lengthening can also be observed in Spanish. The word dos [two] is realized as [do:] in certain dialects. The word-final s isn't pronounced. To compensate, the vowel is lengthened.

Compensatory lengthening is a common phonological process. It usually occurs in the syllable coda and exemplifies sound change. The loss of the syllable-final consonant results in the lengthening of the preceding vowel. As a result, the language preserves the rhythmical quality of the word.