Simply it's a choir. So 16 voices is a choir of 16.
song
You call it harmony.
round
madrigal also, a capella
TEXTURE :)
There is a list of the voice cast at the related link below .
polyphony
song
because you can drive at sixteen and that normally means you get a car.
parts
cantata
Organum
16 years of age. I think that may be why they call it a sweet sixteen.
A short written composition is an essay
A composer named Alessandro Striggio wrote a composition called "Ecce beatam lucem." It is a motet for 40 voices, making it one of the earliest works to include such a large number of vocal parts.
You call it harmony.
birdy