When describing the major scale ive noticed that some material will say
major 3rd or perfect 4th and perfect 5th.  Im guessing a major 3rd is a 3rd
that is not flattened  (Lumpy will straighten me out if Im wrong) but what
is perfect 4th and perfect 5th?  Why not just say 5th?  Thanks.

Thomas

On 05 Jul 2008, "Thomas" <n...@none.com> wrote in
alt.guitar.beginner:

Because there are other flavors of 5ths and 4ths than perfect. They are
obtained by raising or lowering the interval. The common ones are

Perfect 4th (6 semitones from the tonic)
Augmented 4th (7 semitones)
Diminished 5th (7 semitones - same pitch as an +4)
Perfect 5th (8 semitones)
Augmented 5th (9 semitones)

On Jul 5, 4:06 pm, "Thomas" <n...@none.com> wrote:

The names of intervals are based on the major scale that starts with
the lower note in the interval.  The number part of the name comes
from the scale degree of the upper note, and "major" (2nd, 3rd, 6th,
and 7th) and "perfect" (unison, 4th, 5th, octave) intervals are those
whose upper notes appear in the scale.

The reason that some intervals are "perfect" rather than "major" is
that if you invert them, the resulting interval has both notes that
appear in the major scale of the (new) lower note.  For example, a
perfect fifth based on C contains C and G.  Inverting the interval
gives you G to C (a perfect 4th), where C is in the G major scale.
Note that a major third based on C contains C and E.  Inverting this
gives you E to C (a minor 6th), where C is not in the major scale
based on E.

--Cliff (US)

Off by an extra semitone in each case (hint: count frets on a guitar but
don't count where you started!).  But otherwise a good description of
why we use the modifier "perfect".

On 05 Jul 2008, "RichL" <rpleav...@yahoo.com> wrote in
alt.guitar.beginner:

Oops, you're right, I miscounted. This is what I should have said:

Perfect 4th (5 semitones from the tonic)
Augmented 4th (6 semitones)
Diminished 5th (6 semitones - same pitch as an +4)
Perfect 5th (7 semitones)
Augmented 5th (8 semitones)

news:Xns9AD2B4C6D5CB2nilch1@216.196.97.136...

Is there any music theory (which I find arcane) that recognises a dim 4th,
the same interval as a major 3rd?

Tony D

On 05 Jul 2008, "Tony Done" <tonyd...@bigpond.com> wrote in
alt.guitar.beginner:

Yes there is, and you just named it: if you flatten a perfect 4th, you
will have a diminished 4th. But there are next to no practical reasons
to refer the the interval in that way - it's the same pitch as a major
3rd, and you will almost see it referred to as such.

Is there not a need to distinguish between the counted notes being used &
the
notes as defined because of there mechanical , fixed mathematical
properties.

A player might choose to play the 4th or 5th note he is using as anything he
chooses.

The 'Perfect' 4th , 5th etc. is a fixed real world physical relation to the
root note .
(\__/)
(='.'=)
(")_(")  mouse

On Jul 5, 1:54 pm, hcbowman <hcbow...@gmail.com> wrote:

I think I follow this.

But how about the other answer given in this thread (it's called a
"perfect fourth"  to distinguish between augmented fourth and perfect
fourth?

Is that also another reason?

On Jul 5, 9:36 pm, Ravi <Raul.Frem...@gmail.com> wrote:

Hi, and sorry for the confusion.  Each answer is right but only tells
part of the story.

There are two questions being answered:

1.  Why do we have to give the *quality* (major, minor, perfect,
augmented, etc.) of an interval?
2.  When we give the quality of of an interval, why do we use
different systems (major/minor versus diminished/perfect/augmented)
for different intervals?

Other posters answered question #1, saying basically that there are
different kinds of "fourths" -- perfect, diminished, and augmented.
These intervals differ in the number of semitones between the upper
and lower note, so just saying "fourth" is ambiguous.

I answered question #2, saying basically that whether we use major/
minor or diminished/perfect/augmented depends upon what happens when
we invert the interval.  We use major/minor for 2nd, 3rd, 6th, and 7th
intervals because major intervals (say, the major 3rd of F up to A)
become minor intervals (the minor 6th from A to F natural) when
inverted.  We say "perfect" for intervals that stay "perfect" when
inverted, such as A to D (perfect fourth) and D to A (perfect fifth).
In this system, "augmented" intervals (say, the augmented fourth E to
A#) become "diminished" intervals (A# to E, a diminished 5th) when
inverted, and vice-versa.

--Cliff (US)

Cliff (US) writes :

I was under the impression that the term perfect had more to
do with harmony, in that the fifth and fourth are very nice
sounding (harmonious) being low integer ratios of frequencies
(3:2 for the fifth, 4:3 for the fourth).  The term was used
before the even tempered scale was invented so the ratios were
exact.  They aren't any more with the even tempered tuning like
the piano and guitar, which are never completely harmonious
because the ratios are all irrational so the vibrations never
line up.

For more info see Wikipedia :

Perfect fourth : http://en.wikipedia.org/wiki/Perfect_fourth
Perfect fifth  : http://en.wikipedia.org/wiki/Perfect_fifth

Paul P

On Jul 5, 1:40 pm, Nil <rednoise+n...@REMOVETHIScomcast.net> wrote:

IOK, if we just say "a third" it is ambiguous, (is it a Minor 3rd or
Major 3rd?) so we call it a Major 3rd to make it clear .

Likewise, why not just say "Major 4th"? That would seem sufficient to
distinguish it between an augmented 4th.