What is an example of an r-controlled vowel?

An r-controlled vowel is characterized by a vowel that occurs before an 'r' and is altered in such a way that it does not have a clear long or short sound, but instead takes on a unique sound influenced by the 'r'. In this context, the presence of the 'r' changes the way the vowel is pronounced. For example, in words like "car," "her," and "bird," the vowels 'a', 'e', and 'i' take on different sounds because they are directly followed by the letter 'r'.

In contrast, a vowel's sound being typically long does not specifically highlight the influence of 'r', and how a vowel interacts with a consonant can vary widely in English, as can the position of a vowel at the beginning of a word. Therefore, the distinct characteristic of r-controlled vowels is precisely the influence of the 'r' on the preceding vowel sound.