add9 Chords

I posted a request for a lesson, so if the mod feels this thread is overkill, feel free to delete it.

Basically, I have been playing more acoustic guitar lately and trying to learn some songs to work on switching chords. I notice many acoustic songs use add9 chords a fair amount of the time. Now I understand what an add9 chord is - it's just a chord with a 9th added to it. A C major chord would contain the notes C, E, and G, whereas a Cadd9 would contain C, E, G, and D. Easy enough to understand. Same thing can be done for minor chords.

My question is why would a person use these chords? I understand that it has more color to the chord, etc., but I am looking for more of a reason than that. Does it build up to another chord for example? Does it build to a change in the progression structure of a song? There has to be a better reason than "it sounds good".

Thanks for the help!

I've seen them used alongside the simple version of the chord just for variety, and I guess it gives a sense of tension and resolution.

What I don't understand though, is why there has to be a better reason than it sounding good. Music theory exists to help people achieve 'good' sounding music. If it sounds good to them, then why wouldn't people use add9ths, and why would they absolutely need another reason?

Well Doz, there doesn't have to be a better reason. I just thought there might be an actual music theory reason for using them. That's all I really meant by it.

Theoretically, there is no reason to use any extensions beyond the 7th, i.e. 9th, 11th, 13th, they're just there to add some colour/variety. However, if the chord didn't contain a 3rd, the 9th or 11th would be functioning as a suspension instead and would therefore be used to provide tension that resolved down (11th) or up (9th) to the 3rd. Make sense?

Variety is the spice of life and all that jazz :)

Afro

Yeah, but the music theory behind it would be in place because it sounds good (or pleasing), right?

Afro, when you talk about 9th and 11ths, do you mean like sus2 and sus4 chords?

Yeah, he does. Taking your example, the Cadd9 chord without the third would be a sus2 chord.

I've read a lot of chords about this kind of chords but one thing I never understood is how can there be a 13th note of any scale. So since it can't be the 13th, 11th or 9th note of any scale then what is it the thirteenth note of? I mean where do you start counting and what do you count? Why isn't the name of that interval used like when you say the major third?

Well, It's thirteenth of the scale, going past 8 as the octave. The 9th is a 2nd an octave up. But since the chord contains a 3rd, you call it a 9th. Which was why they mentioned sus2 and sus4 above. If you don't have a third, it's sus2 or sus4, if you DO have a third, it is add9 or add11 or whatever.

Exactly what Zula said - nice one :)

Afro