Can irregular nouns change their vowel sound to make it plural?

No, irregular nouns don't change their vowel sound to become plural.

Irregular nouns have their own unique ways of forming plurals, which don't follow the typical rules of adding "-s" or "-es".

Here are some examples of how irregular nouns form plurals:

* Adding "-en": child - children

* Changing the vowel sound: foot - feet, tooth - teeth

* Staying the same: sheep - sheep, deer - deer

* Having different forms: man - men, woman - women

While some irregular nouns might have different vowel sounds in their singular and plural forms (like "foot" vs "feet"), this change is not a general rule for irregular nouns. It's a specific characteristic of those particular words.

Let me know if you have any other questions!