Why do er, ir, re and ur usually sound the same?

What the schwa?

Butter, bird, centre and curl all have the same vowel sound because they all represent the same vowel sound, which is a schwa sound followed by an r sound. The schwa sound is a very short and neutral vowel sound that is often heard in unstressed syllables. It is the most common vowel sound in English, but it is also the most difficult to define.

The reason why these letter combinations all represent the same vowel sound is because of a sound change that occurred in the history of the English language. In Old English, the letters E, I, R, and U all represented different vowel sounds. However, over time, these vowel sounds merged together to form the schwa sound.

This sound change is known as the Great Vowel Shift, and it was one of the most important sound changes in the history of the English language. It affected the pronunciation of most of the vowels in English, and it is one of the reasons why English spelling is so complex.

Today, the er, ir, re and ur letter combinations all represent the same vowel sound, but they are still used in different words. This is because the English language is a conservative language, and it tends to retain old spellings even after the pronunciation of the words has changed.