OUL (would) Sound Word List
The /oul/ sound is one of four sounds you can think of as beginning with the letter “o”. The four sounds are /ow/ (cow), /oy/ (toy), /oo/ (zoo), and /oul/ (would).
Of the 7,000 words in the database constructed from a popular children’s dictionary, 25 of them are one-syllable words in which the vowel sound is /oul/. There are only three different spellings, "oo" (book), "u" (bush), and "oul" (could).
The "oo" spelling is the most common. Once the words under the other two spellings ("u" and "oul") are learned, there will be very few new words encountered in multisyllable words that are not just derivatives of those words such as bully and wouldn’t.
A note on the naming of this sound, /oul/. That spelling is found in only three words, and their derivatives, "would", "should", and "could". Both the "oo" and the "u" spellings of this sound are already used to name other sounds. Using "ou" would work, but that would require explaining the "ld" at the end of each of those three words. So /oul/ seemed a reasonable choice for describing this sound.