I am teaching myself sight singing right now, and I know how to sing single note(the left one as pictured) on both treble clef and bass clef but get stuck in multiple notes(the right one as pictured). Assuming that is the bass clef, do I need to sing out as mi do at the same time or just either one of them? Thanks.
1Either begin practicing overtone singing or slur the notes...– Tim Burnett - BassistApr 8, 2017 at 17:59
If we exclude the cases where the score requests Overtone singing (very rare, quite specialized), it must mean that there are multiple voices (which implies multiple people) singing at the same time.
Here's some random example from Wikipedia (from the page Four-part harmony):
In it you can see 4 voices that would be sung by at least 4 different people at the same time.
Notice in the OP's example, the stem is one way. In SATB, the T tails are up, B tails down.– TimApr 8, 2017 at 6:47
1Good point, however, it's not unusual for hand-written scores. Another thing that I forgot to mention: occasionally song scores use multiple notes with the same stem to indicate that in different verses different notes can be chosen, or that back vocalist can pick the alternative note to sing. Apr 8, 2017 at 6:53
Generally speaking (or singing!), a person only sings one note at a time. It's possible to sing two, but the vast majority would only sing one. I guess you have the choice here, sing mi, then do; or mi then mi again.