#1
I'm trying to learn theory and I really want to make sure I understand intervals perfectly first. What I just don't get is why the perfect fourth of F is Bb and not A#.

I've always understood that Bb and A# are essentially the same note but now I find out that they are the same pitch but not really the same note.

Can someone shed some light on this, please?
Quote by Trowzaa
I immediately clenched my butthole after reading that...
#2
Bb and A# are exactly the same things.

Edit: Think of it this way, one number below 3 is 2, and one number above 1 is also 2. So the note between B and A is below (flat "b") B, and above (Sharp "#") A


Edit: And then it seems im totally wrong. Damn
Last edited by MossyMan at Jul 11, 2009,
#3
The perfect fourth of F is Bb and not A# BECAUSE in the key of f major A# is not considered to be part of the key. The key signature of F major if you write it on a staff appears as one flat on the B note. Its just how it works out...Its a fourth. If it was A# it would be an augmented third.
Quote by Rockford_rocks
Who the hell is Mcjagger?





Oh my god, do you mean Mick Jagger?


haha
#4
I'm not even making sense to myself today, so I'll try (in my horrible state of sleep deprivation) to explain.

1st F - F Unison
2nd F - Gb/G/G# minor second/major second/augmented second
3rd F - Ab/A/A# Minor third/major third/augmented third
4th F - Bb/B Perfect fourth/augmented fourth
5th F - Cb/C/C# Diminished fifth/perfect fifth/augmented fifth

As you can see each degree is named with a letter. F to A, regardless if it's an A sharp or flat or whatever, is always a something third. It's the same with F to B something, it's always a fourth.
        ,
        |\
[U]        | |                     [/U]
[U]        |/     .-.              [/U]
[U]       /|_     `-’       |      [/U]
[U]      //| \      |       |      [/U]
[U]     | \|_ |     |     .-|      [/U]
      *-|-*    (_)     `-’
        |
        L.
#5
A fourth spans four letters of the musical alphabet like F G A B
A perfect fourth spans four letters and is a distance of 2.5 tones or 5 semitones, like F - Bb

A third spans three letters of the musical alphabet like F G A
A major third spans three letters and is a distance of 2 tones, like F - A
F - A# is still a third (because it spans 3 letters), but it is a distance of 5 semitones. It is one semitone greater than a major third, and so it is called an Augmented Third.
My name is Andy
Quote by MudMartin
Only looking at music as math and theory, is like only looking at the love of your life as flesh and bone.

Swinging to the rhythm of the New World Order,
Counting bodies like sheep to the rhythm of the war drums
Last edited by Ænimus Prime at Jul 11, 2009,
#6
Quote by demonofthenight
I'm not even making sense to myself today, so I'll try (in my horrible state of sleep deprivation) to explain.

1st F - F Unison
2nd F - Gb/G/G# minor second/major second/augmented second
3rd F - Ab/A/A# Minor third/major third/augmented third
4th F - Bb/B Perfect fourth/augmented fourth
5th F - Cb/C/C# Diminished fifth/perfect fifth/augmented fifth

As you can see each degree is named with a letter. F to A, regardless if it's an A sharp or flat or whatever, is always a something third. It's the same with F to B something, it's always a fourth.

Best explanation as I see it. The notes A-G all appear in the F scale, and they all appear once - what changes is their quality (flat/natural/sharp)...so 4 steps from F in the F scale is F-G-A-B.
#7
Quote by vartanspartan
I'm trying to learn theory and I really want to make sure I understand intervals perfectly first. What I just don't get is why the perfect fourth of F is Bb and not A#.

I've always understood that Bb and A# are essentially the same note but now I find out that they are the same pitch but not really the same note.

Can someone shed some light on this, please?


Tis simple my friend. When dealing with theory like this, those are really two different notes.

The way you determine if something is a 4th or a 5th etc. is by counting the lines on the sheet music away from the root note.

So if your looking at F on the treble clef and count 4 spaces and lines above it, you will land on the note B. So we can agree that a 4th away from F is B. However we still need the specific name for the interval. As you know a perfect 4th is not F to B, it is F to Bb.
The reason you cannot say that a perfect 4th away from F is an A# is because in order to get to A on the treble clef only have to move 3 spaces to get to an A note, making it a 3rd and not a 4th.

SO in order to keep it a 4th you must instead change the note so it is the same as the A#, you do this by lowering the B to a Bb.

There ya have it, your perfect 4th from F to Bb.

Does that make since?
#8
Thanks guys. It's not so much that I "get it" now but I do accept it more now.

edit: Thank you Guitarfreak777!!! Now I do get it.
Quote by Trowzaa
I immediately clenched my butthole after reading that...
Last edited by vartanspartan at Jul 11, 2009,
#9
Quote by vartanspartan
Thanks guys. It's not so much that I "get it" now but I do accept it more now.

edit: Thank you Guitarfreak777!!! Now I do get it.


np dude, PM me if you have any other questions
#10
It's pretty simple actually. Look at this chart real quick of the numbered musical alphabet starting with F:

F G A B C D E
1 2 3 4 5 6 7


Anything having to do with 2nds away from F (minor seconds, major seconds, augmented seconds, triple super diminished seconds, whatever) will always use the letter name G. Anything having to do with 3rd away from F will always use the letter name A, and so on. So, a perfect fourth from F has to use the letter name B because it is the 4th letter away from F in the musical alphabet. Likewise, an augmented 3rd away from F, which is enharmonic to a perfect fourth, would be A#.

Most likely you won't have to think about it this way once you get further into theory and the correct letter name will come to naturally, but for now, reference this technique to make sure you're spot on.

Edit: GuitarFreak's explanation is a less linear explanation of what I said above. If you examine both closely you will see that they don't conflict
i don't know why i feel so dry
Last edited by Eastwinn at Jul 11, 2009,
#11
Most common musical scales always include "A B C D E F G". Thus, an F scale must go "F G A Bb C D E F". Were it to go "F G A A# C D E F," it would skip the B part of the scale, which would be wrong. So when you're playing in the F scale, you always refer to the 4th note as Bb and not A# if you want to be theoretically correct.
If man is 5, if man is 5, if man is 5,
then the Devil is 6, then the Devil is 6, then the Devil is 6, the Devil is 6,
And if the Devil is 6,

then God is 7, then God is 7, then God is 7
This monkey's gone to heaven.
Last edited by theking182 at Jul 12, 2009,