A musical interval is the distance of pitch between two notes. They may be described as harmonic (the two notes heard simultaneously) or melodic (proceeding each other).
Figure 1: The interval Minor 6th.
To measure an interval's size, two factors are taken into account: quantity and quality.
An intervals quantity is written numerically (e.g. C to G is a 5th).
To identify an intervals quantity, simply add up the number of lines and spaces between the two notes, including the lines and spaces containing the notes themselves. For example:
Figure 2: Counting five steps from C to G makes a fifth.
The following is a list of different interval quantities available:
If our two notes are sitting on the same line or space, the interval is unison. If the interval is eight lines and spaces apart, it's an octave.
Interval quality is used to describe interval quantity (e.g. Major 3th). It's what gives an interval it's distinct sound.
While quantity is known by counting the number of lines and spaces written, quality requires counting the full amount of semitones from the first to second note. For example:
Figure 3: There are four semitones from F to A (F, F#, G, G#, A) which makes a Major 3rd.
An interval's quality may be described as one of the following terms:
- Major (maj.)
- Minor (min.)
- Perfect (perf.)
- Augmented (aug.)
- Diminished (dim.)
Because some intervals sound more harmonious than others, and others more perfected, it is categorized that 2nd's, 3rd's, 6th's and 7th's may be major or minor and unison's, 4th's, 5th's and octave's may be perfect.
This completes our vocabulary for standard intervals:
An interval six semitones in length is called a tritone, which is the same length as an aug. 4th or dim. 5th.
Accidentals may be used to sharpen or flatten either note of an interval and give it a new quality:
Figure 4: Five intervals with the same quantity, but different qualities.
When accidentals are used to alter an intervals quality, the following four rules are implied:
First rule: If any major interval is flattened by a semitone, its quality becomes minor.
Second rule: If any minor interval is sharpened by a semitone, it becomes major.
Third rule: If any major or perfect interval is sharpened by a semitone, it becomes augmented.
Fourth rule: If any minor or perfect interval is flattened by a semitone, it becomes diminished.
...and that completes our vocabulary for all intervals used in western music:
|perf. uni||*dim. 2nd||0|
|maj. 2nd||dim. 3rd||2|
|min. 3rd||aug. 2nd||3|
|maj. 3rd||dim. 4th||4|
|perf. 4th||*aug. 3rd||5|
|tritone||aug. 4th||dim. 5th||6|
|perf. 5th||*dim. 6th||7|
|min. 6th||aug. 5th||8|
|maj. 6th||dim. 7th||9|
|min. 7th||aug. 6th||10|
|maj. 7th||*dim. 8ve||11|
|perf. 8ve||*aug. 7th||12|
* Not very usable.
All intervals that share the same row are enharmonic intervals because, although they differ from each other in name, they don't in number of semitones.
The following are some examples for your understanding:
An interval inversion is when either note is raised or lowered an octave to impose an entirely new interval:
Figure 5: A perf. 5th becomes a perf. 4th when inverted.
Compound intervals are those greater than an octave in length. They may increase their numeric quantity greater than 8 (e.g. maj. 9th), or simply be called a compound maj. 2nd.
Figure 6: A maj. 9th or compound maj. 2nd.
Interval Recognition (Songs)
It is commonly practised when recognising an interval by ear (aurally) to use the first interval, or one of the first intervals, of a song as a reminder. By singing the first two syllables of Amazing Grace (A-maz), it recalls we are hearing a perf. 4th.
The following is a list of songs which may be used as a reminder for each interval:
|Unison||O Little Town of Bethlehem||O Little Town of Bethlehem|
San Francisco (Left my heart)
I Remember You
I'm Getting Sentimental over You
Bye Bye Black Bird
It's Been a Hard Day's Night
Joy to the World
Stella by Starlight
The Lady is a Tramp
Shall We Dance (The King and I)
Rudolf the Red Nosed Reindeer
My Funny Valentine
Body and Soul
Mary had a Little Lamb
Deck the Halls
Three Blind Mice
The First Noel
Georgia on my Mind
A Foggy Day
The Impossible Dream
Somewhere my Love
Frosty the Snowman
What is This Thing Called Love?
When Irish Eyes are Smiling
This Old Man
Star Spangled Banner
Oh When the Saints
I Can't Get Started
While Shepherds Watched
Come Rain or Come Shine
Here Comes the Bride
Someday my Prince Will Come
Hark the Herald Angels Sing
Oh Christmas Tree
We Wish You a Merry Christmas
All the Things
Song for my Father
Love me Tender
Auld Lang Syne
Shave and a Haircut
Oh Come All Ye Faithful
Softly, as in a Morning Sunrise
I Didn't Know What Time it Was
Almighty Fortress is Our God
I've Been Working on the Railroad
Maria (West Side Story)
Theme from 2001
Theme From Peanuts
7 Steps to Heaven
Have You Met Miss Jones?
The Way You Look Tonight
Mozart's Minuet in G
Love Story (third and fourth notes)
Morning of the Carnival
Go Down Moses
The Entertainer (third and fourth notes)
Love Story Theme
My Bonnie Lies Over the Ocean
Jingle Bells - Verse - "Dashing Through the Snow"
You're a Weaver of Dreams
Nobody Knows the Troubles I've Seen
Gonna Lay Down My Sword and Shield
There's a Place for Us (West Side Story)
Old Star Trek Theme
Somewhere (West Side Story)
I'll Close My Eyes
Theme from American in Paris
Cast Your Fate to the Wind
Theme from Fantasy Island
I Love You
"Hee Haw" From the Grand Canyon Suite
Somewhere Over the Rainbow
A Christmas Song
There's No Business Like Show Business (Notes 2-3)
Willow Weep for Me
Also see Accidentals | Scales.