What is the common name for the sound represented by the symbol 'ə'?

The sound represented by the symbol 'ə' is commonly known as the schwa. The schwa is an unstressed and mid-central vowel sound in English and many other languages, typically found in unstressed syllables. It occurs in words like "sofa," "banana," and "support," where the vowel sound is quick, relaxed, and less articulated than stressed vowel sounds.

Understanding the schwa is crucial in phonetics because it highlights the importance of stress patterns in pronunciation. In contrast to the other vowel sounds listed, such as short "u," long "a," and open "e," which are distinct and stressed sounds, the schwa does not have a specific place of articulation and serves to enhance the rhythm and flow of speech.