For learners of phonics, the schwa plays a key role, since it is the most common vowel sound in the English language; any vowel, typically in an unstressed syllable, may be pronounced as a schwa. The schwa has an "uh" sound, heard in the first syllable of the word "about" and in the words "but" and "the." The schwa is the only phoneme, or distinct unit of sound in English, with its own name.
The schwa is represented in pronunciation guides by an upside down lower case e. The word "schwa" comes from the ancient Hebrew word "shva," where it indicated emptiness or the lack of a vowel sound. In the early 19th century, Jacob Grimm, of the Brothers Grimm, incorporated the term into European linguistics and altered it to a German spelling.
In practice, the schwa is typically considered a third sound for each vowel, distinct in sound from the long and short version of the vowel. It is a neutral sound that may vary slightly depending upon the consonants that surround it in a word.
In languages such as English, French and Russian, the schwa is typically used in unstressed syllables, but Albanian, Bulgarian, Slovene and Afrikaans allow stressed schwas. Common English pronunciation occasionally deletes a schwa in a mid-word syllable that comes after the stressed syllable, such as the "o" in "chocolate" or the "e" in "camera."