Here's why:
* The vowel sound in "joyous" is a long "o" sound. This is similar to the "o" sound in words like "go" or "toe".
* Short vowel sounds are typically found in words with one vowel and a consonant after it. Examples include "cat", "dog", and "sun".
Therefore, "joyous" has a long "o" sound, not a short vowel sound.