Author Topic: Need some simple help with Perfect Intervals  (Read 723 times)

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alanwaston

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Need some simple help with Perfect Intervals
« on: January 09, 2017, 01:36:29 AM »
So I am very confused on this and I have looked around alot in my textbook for a better explanation but I cannot find it.

The questions ask me to name all the perfect intervals. The examples the text's says they are all perfect (Unison, 4th, 5th, and 8ves of course). So I looked through the questions, and in the back of the book its says questions 4. and 7. are not perfect intervals and I am here to ask why is this? Here are the two questions I dont get.

No. 4 is In (Bass Clef) from A to E Flat I know this is a 5th so why is it not perfect. Is this just considered diminished? And if so why is it diminished?

No. 7 Is (Bass Clef) from D Flat to A. Again why is this not a perfect interval?

I need an explanation because I can not figure it out haha I know its extremely elementary. Any help would matter alot to me  thank you again! and if anyone could maybe link a better explanation of intervals I would like that also .


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« Last Edit: February 10, 2017, 12:10:28 AM by alanwaston »

Offline Mahlerian

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Re: Need some simple help with Perfect Intervals
« Reply #1 on: January 10, 2017, 06:50:07 AM »
So I am very confused on this and I have looked around alot in my textbook for a better explanation but I cannot find it.

The questions ask me to name all the perfect intervals. The examples the text's says they are all perfect (Unison, 4th, 5th, and 8ves of course). So I looked through the questions, and in the back of the book its says questions 4. and 7. are not perfect intervals and I am here to ask why is this? Here are the two questions I dont get.

No. 4 is In (Bass Clef) from A to E Flat I know this is a 5th so why is it not perfect. Is this just considered diminished? And if so why is it diminished?

No. 7 Is (Bass Clef) from D Flat to A. Again why is this not a perfect interval?

I need an explanation because I can not figure it out haha I know its extremely elementary. Any help would matter alot to me  thank you again! and if anyone could maybe link a better explanation of intervals I would like that also .


4. A perfect fifth from A would go to E natural, not E flat, and any interval that is one semitone smaller than a perfect interval is called diminished.  It forms a diminished fifth, which is a famously dissonant interval.

7. A perfect fifth from D-flat would go to A-flat, not A natural; any interval that is one semitone wider than a perfect interval is called augmented.

Augmented and diminished intervals are always considered dissonant, and as such cannot be perfect consonances.  That may seem confusing, especially as some of them are enharmonic to (use the same notes on the keyboard as) consonances, but in traditional theory as well as in traditional practice the distance from D-flat to A is not thought of as being the same as D-flat to B-double flat.
« Last Edit: January 10, 2017, 06:51:42 AM by Mahlerian »

Offline Monsieur Croche

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Re: Need some simple help with Perfect Intervals
« Reply #2 on: January 11, 2017, 04:51:26 AM »
This has as much, or everything, to do with "musical grammar," i.e. appropriate note names (A B C D E F G) and their spelling, regardless of the key you are in.

The QUANTITY of any interval, 2nd, 3rd, 4th, 5th, etc. is found in how many alpha (letter) names distance apart any two pitches are.

The QUALITY of any interval (perfect / major / minor/ augmented = enlarged / diminished = lessened) is found in the number of half steps between the two pitches.

Regardless of any alterations using accidentals, in the key signature -- or written in, if spelled C up to E, the quantity is 'a third.'
It is the distance in the number of half-steps from one note to the next that determines the quality of Perfect, Major, Minor, Augmented (increased) and Diminished (lessened.)
C up to E happens to be major, with four additional half steps distance above the C.
C up to Eb  is quantatively still 'a third' because it is still 'C to an E,' but the Eb is three additional half-steps distance above (the defining number of semitones apart qualifying minor)
This is a constant.
Think of a keyboard, and picture, 'white notes in the key of C.'
C up to E and C down to A.  Both thirds.  Count the number of half steps between, the C up to E is a major third (four half-steps above) while the C down to A is a minor third (three half-steps below.)


IF you instead spelled your perfect fifth as C, Gb, that is no longer 'perfect' (perfect being a quality like major or minor).  That Gb lessens the number of half-steps that make a perfect fifth 'perfect,' and in lessening it, you have diminished it.
C up to G = 5th, perfect
C up to Gb = 5th, diminished.
C up to F#, the same no. of half-steps apart, because it is C up to F, is an augmented fourth :-)
C up to G# = 5th,  augmented. C up to Ab, the same distance, is a minor sixth.
 
Count / measure the distance between the letter / alpha names to determine the general quantity, 5th,m 7th, 4th, etc. 
Count / measure the distance of the number of semi-tones between the pitches to determine their quality, perfect, major, minor, diminished, augmented.


Best regards
« Last Edit: January 19, 2017, 04:46:22 PM by Monsieur Croche »
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