Here's why:
* Short vowel sound: The vowel sound in "soap" is a short "o" sound, like the "o" in "hot" or "lot".
* Long vowel sound: A long vowel sound is typically pronounced the same way as the letter's name, like the "a" in "fate" or the "e" in "tree".
Therefore, the vowel sound in "soap" is a short vowel sound.