Partial voicing in music is like singing or playing a note, but not all the way. Imagine holding your breath and making an "uh" sound, like you're thinking. When you sing a note with partial voicing, it's like you're doing that while you're singing.
When you sing normally, you use your vocal cords to vibrate and make the sound. But with partial voicing, you don't let your vocal cords vibrate all the way. It's like if you were to pluck a guitar string, but hold it down with your finger so it doesn't vibrate all the way.
Partial voicing can add a cool effect to music, like a breathy or airy sound. It's often used in genres like jazz and pop, and singers use it to create different moods or emotions in their songs.