Questioning the Why

I have a question concerning a song I just learned from tabs the other day, it is one of my favorite songs "Nutshell" by Alice in Chains. Below is the tabs (I apologize for the spacing, I had to add some "-" to try to get the chords to line up properly).

Em7 G D Cadd9
----------3------2---0----0----0-----0-----0----------0-----0---0----------
--3---3--3---3--3---3----3----3--3--3-----3---3--3--3-----3---3--3--3---
--0---0--0---0--2---0----0----0--0--0-----0---0--0--0-----0---0--0--0---
--2---2--0---0--0---2----2----2--2--0h2--2---2--2--0h2---2---2--2--2--
--2------2-----------3----3-----------3-----3----------3-----3--------------
--0------3--------------------------------------------------------------------

. Em7
--0--0--0--0----3--3---------
--3--3--3--3----3--3---3--3--
--0--0--0--0-------0---0--0--
--2--2--2--2-------2---2--2--
---------------------2---2--2--
---------------------0---------

My question is about the why. Why did the artist choose these chords? Is this some sort of progression that is not in common internet literature? I guess maybe what I am really asking is why does he choose Em7 as opposed to Em? Why does he choose Cadd9 instead of C? Is it due to a progression or is it just because he liked how it sounded?

its likely he just liked how it sounded, sometimes playing sevenths or add9's give the progression a little more character, sometimes they can change the feel of a song all together

I've never heard that song before, but just gave it a listen and I really like it. In fact, I haven't listened to a lot of Alice in Chains but what I have heard is great - might have to give them more of a listen in future I think.

Anyway, now to answer your question. The progression itself is not the most common one out there, but it is used a lot. The vast majority of rock and pop music (though pop less-so, seems these days the fewer chords and notes and more drum loops, the better, but that's a whoooole other area) use progressions made up of chords I, vi, IV and V in a major key (with that particular progression probably being the most common) but put those four chords in any order and it will sound good. The reason? It just does; once you're past the theory of music, all you've really got to go on is how it sounds.

The theoretical reason as to why he chose Em7 instead of Em and Cadd9 instead of C is that adding more notes into a chord inevitably gives it a fuller sound (more notes = more sounds), but more importantly it stops the chords sounding more rigidly major or minor. It kind of confuses the ear by bombarding it with more tones than just the standard root, 3rd and 5th so that you tend to hear more a cluster of sounds rather than chords that noticeably move between sounding 'sad' (minor) or 'happy' (major). Again though, if that's not a good enough explanation, you'll have to settle for the fact that it simply 'sounds' good.

The other reason why those particular extensions are used is that they help one chord flow more smoothly into the next by finding common notes shared by neighbouring chords. For example, look at how D is followed by Cadd9 - they both share that D note on the B string -in the D chord it functions as the root, and in the C chord it's the 9th. If that 9th wasn't there and it was just a normal Cmajor chord, there would be no shared notes, therefore a less smooth transition between chords. Again, look at how the Cadd9 moves into the Em7 - the 9th in the C is the 7th in Em. Shared notes, smoother transition.

Sorry about the essay, but that should hopefully clear things up for you. I remember asking the same question when I first joined this site years ago, and I just know that's the sort of answer I would have wanted. Anyway, any more questions, please write back!

Afro

P.S. Have just discovered the joys of syntax thanks to guitarslinger's lesson - hence all the bold type!!

Wow. Thanks, Afro. I Loved the answer.

Great answer Afro, but I would say that vi, IV, I, V is more common than that progression :)

(That would be Em, C, G, D)

I reckon it's open for debate Jeff, but I've edited my post accordingly!

Afro

Thanks for the responses everyone! Afro, the paragraph about sharing notes is pretty much exactly what I was looking for. Why did he choose the particular chords and why did he switch to the next chord? Because of sharing notes, that is cool. That could really help me out a lot when thinking of my own stuff in the future. I try hard to use some songs to practice playing chords and switching from one to another, but I find that asking questions like this one and trying to learn the reasons the artists made the songs the way they do really helps me learn and take something else from playing songs, besides just practicing.

Oh and Afro, look into the album "Jar of Flies" if you want some more Alice in Chains, that si the album the song is on. imo, they had a pretty diverse style throughout their existence so that album would be most like the song "Nutshell".