A song might have different types of chords like major, minor, seventh, and so on. We know different types of chords play with our emotions differently. For example, seventh chord creates tension in mind. I wanna know how to sing them in a song or more elaborately, how our singing voice adjusts different types of chords like major, minor or seventh and so on...within the same song?
As a vocalist, you will probably never sing more than one note at a time (although as jjmusicnotes pointed out some vocal styles sing multiple notes) and most likely it will be a note in the key the song is in so if you can sing all the notes of that scale you should be good. Even if you sing an arpeggio of a major, minor, or seventh they are usually just notes in the key. You could technically sing the same note over and over again and have the chord playing behind you change. One example of this in A minor is you can sing an E over an A minor chord, a C major chord, and a E7 chord. The note you sing may not change, but the chords around it might.
There may be tricky intervals that you may need to sing and that comes with practice, but it shouldn't have much to do with the chords themselves.
The quality of a singer's voice doesn't change from singing a 6th, or 7th. The underlying mix of notes will change (harmony), but the timbre will remain stable. A different word/vowel sound may have a changed inflection, and where a particular word is, in a bar or line will sound different - as in emphasis, but that's all.
In the Western world, Europe, etc. most vocals are sung using one note at a time, -I don't know where you're from - so singing more than one note, to make a chord, is quite unusual.So, only using one note at a time as the criterion, we can't sing chords anyway, thus making the idea of adjusting to different chords very difficult.
I wonder if you mean to ask about singing a particular note out of an underlying chord, or even a note that doesn't belong to that chord.E.g. singing the 6th over a maj6 chord will sound quite different from singing the root. It sort of highlights the fact that it's not just another major , but has an addition.I.e. it shows more about the quality of the accompaniment.
It seems that you are talking about singing improvisation. For that matter, you should get into studying harmony, so you will know wich note of a chord you are singing, and moreso, get into harmony chord functions. Then you'll realize that for each of those chords you pretend to sing in, there is an harmonic field: predetermined possible notes by the function of that chord at that place in the overall harmony. Among those notes, you will find that some are more emotional expressive - because they will conotate the harmonic function of that chord more explicitly - and others are less tensioned.
For example, take a simple harmony: | C7+ | Dm79 | G79- | C7+ |...
At the first bar, if there is no accompaniment and the melody sings only C and G notes, we will never find it is a Major harmony. So, the 3rd is totally relevant. And so, if the B is not sung, we will not hear the 7th. You sing Jonic.
Second bar: most relevant notes: D and F (so it's minor). Expressive notes: C (7th) and E (9th). You sing Doric.
Third bar: relevant: G. Expressive: Ab (that's really expressive, because it is strange to the harmony). In this place of a dominant function, the B is also very expressive, it is the sensible note. All the traditional harmony grew from it. Sing it. It claims for the C. And F is very expressive because claims for the E. In this scenario, F and B form a tritone. You sing Altered Mixolydian b9 (and b13 -- Eb instead of E nat if you will).
Also remember that jumps express drama. And it feels different when the jump is up or downward. High pitches often thrill expectators.
Hope it helps to point out ways.