What are Practical Uses for Intervals?

[Simo]

Ive been playing for 15 years and have only ever known some basic theory from my teacher i had years ago. I can play pretty well and now im trying to understand why things i know from ear sound good in music theory.

Can anyone please explain some practical uses for intervals?

E.g. intervals in C.
c-d is a major 2nd interval
c-e is a major 3rd interval

What is a practical use for this and how will that knowledge help me when i play music.

By practical use i mean e.g:
The Dorian mode is a minor scale: The practical use for that is if you what to improvise over something played in say A Minor you can play the A Dorian mode and it will fit.

Thank you

[gck]

Intervals are something like the "very basic" of music theory. Like learning to count 0,1,2,3,4, etc.. before you can learn some serious mathematics. Without a proper knowledge of intervals you can't really understand anything else about music theory in dept. Intervals are the smallest bit of music you can think of...

Practical use, well, there are LOTS!!

1) Learn your spellings: if you know the spellings of all the intervals, you don't need to learn any scales by heart or something like that. Also, you'll have a certain advantage over people who would go through a scale in their mind when they are looking for the fifth (or whatever) when you have simply learnt it. It takes time to learn all the spellings but every music teacher I've had so far (piano, violin and a few guitar lessons) was very pleased to see that they forced me to learn it in elementary school when I was a child... (My el. school was very music orientated, everyone had to learn an instrument, etc..)

2) You can build any chord when you know the intervals. For example, when you are asked for a D major chord, you simply get a D, a major third and a perfect fifth up and have D F# A, and you can even double check by knowing that F#-A is a minor third. For example, if someone told you the chord was D Gb A because he looked on his instrument you could tell him he's wrong because D-Gb is not a major third....

3) If you are really clever you learn the special sound of the intervals as well: every interval gives its two notes a different shade of sound (hard to explain) but there's something that allows me to distinguish a minor third from a major third, for example, because there's something special about the sound (kinda like the "major chord sounds happy and a minor chord sounds sad"-thing... very hard to explain in words). Anyways, if you can hear the intervals and spell them correctly, that is a really good foundation for everything else (Apart from the fact that you can play most guitar solos by ear now!).
By the way, knowing the sound is also practical for improvising: when you have a certain sound in your head it's very easy to get it on the instrument if you can identify the interval(s).

So basically, intervals are the foundation of music theory and relative pitch, learning them is really worth the time!!

[Josh Redstone]

World's most popular interval; a power chord.
I like to play a lot of 5ths and 4ths.