Maybe they're more like Tyrial the Archangel (from Diablo 2)... that would explain why they're always saying "do not be afraid" when they come with a message from God.
The idea of angelic voices as prepubescent boys (NOT girls - different voice quality entirely) comes from all those English choirboys singing the Psalms after the first lesson. Lewis had something to say about that too -- the incredible contrast of the pure disembodied clarity of the boys' voices singing psalms of vengeance and power . . .
The "English sound" is a clear, straight tone, devoid of the vibrato that we associate with a mature voice. Part of that of course is that we're exposed to pop music all the day long. I was taught to sing with zero vibrato, and in my upper register I sound as much like a choirboy as you could expect of a 51 year old contralto . . . < g >
Precisely. The Bible doesn't lead one to expect the insipid from angels.