# What's the point of 7, 9, and 11 chords? (I understand the purpose of the V7)

I was taking a look at "How Deep Is Your Love" by Bee Gees, and had a question about the verse progression. Do these 7, 9 , and 11 chords have a practical purpose? Or are they just for some extra flavor? I'm wondering if I should consider these scale degrees in my progressions more often. Here's how it looks:

• What function does any chord have in any song? Does it make it sound better? Then that's its function. Commented Sep 21, 2018 at 22:41
• 'Function' means something deeper than that in harmony. In this excerpt A7 has a dominant function towards the Dm7 chord that follows. If it had been A9 or A13 the function would be the same. Be careful about that V11 description of F/G. It's ambiguous, to say the least. Stick with F/G if you want the right notes to be played. Commented Sep 22, 2018 at 13:28
• This looks like Hooktheory's analysis to me. Hooktheory sometimes makes questionable analysis judgements, like calling that chord V11 (not necessarily wrong, but usually analysed differently). Commented Sep 23, 2018 at 17:01

Functionally, the extensions aren't changing the chord itself. A dominant chord works the same way regardless of whether it's V or V13(♭9,♯11). That said, usually the chord F/G isn't analysed as V11. There's certaintly no harm in learning how to use extensions, however, as they do add a certain colour to progressions.

They don't change function, they change colour.

I'm going to use a simpler example than the Bee Gees, because this ought to be recognisable from just 2 chords, once we add the tension.

OK, yes, it's "just flavour" but... try playing [at perhaps 70-80bpm, quite slow, simple crotchets will do, pedal down is nice] one bar of the chord A Maj [no inversion, simple root triad] with a simple bass note one octave below, then one bar of B Maj, similar configuration, round & round, one bar of each.

OK, it's 'fine' but it could get dull quickly. It also somehow sounds like we're changing key every bar... so let's fix that...

Let's add some flavour - in this case not only flavour, but tension... see how this almost forces the next chord...

Same bar of A, bar of B... but this time, only play B in the bass, never the A.
The B in the bass against the A Maj in the right hand makes this a B Maj 11, or you might prefer to call it A Maj/B, but the result is the same.

Tell me you didn't recognise that famous intro in one bar.
Once you've recognised it, you can change the simple crotchets to the slightly more complex timing the record had, it's not much of a stretch.

• How does A/B make Amaj11? Seems to me it would make A(add9) instead. Or do you mean the polychord A major played over B major? Which would make B-D♯-F♯-A-C♯-E, which is B11? Commented Sep 21, 2018 at 19:06
• D'oh!! BMaj11, will edit post. Commented Sep 21, 2018 at 19:10
• Oh, Bmaj11 with no 3rd, no 5th? That makes sense. Commented Sep 22, 2018 at 18:32