Here's why:
* Soft consonants are sounds produced with the tongue touching the front of the mouth, like "t", "d", "s", "z", "n", "l", "r", and "j".
* The "a" sound in "age" is pronounced like the "a" in "father", which is made with the tongue further back in the mouth.
Therefore, the sound "a" in "age" is a vowel, and the "g" is a soft consonant.