Learning Objectives
- Learn how to identify the quality of seconds, thirds, sixths, and sevenths.
Intervals VII: Spelling and Identifying Major/Minor Intervals
Counting Semitones
One way to identify a given major/minor interval is to count the number of semitones it contains. As discussed previously, this works well for small intervals, but is time-consuming for larger intervals. The following chart provides a summary of the interval qualities we have discussed, along with the number of semitones they contain.
| Semitone chart | |||||||||||||
| Interval Quality | P1 | m2 | M2 | m3 | M3 | P4 | A4/d5 | P5 | m6 | M6 | m7 | M7 | P8 |
| # of Semitones | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
Although this list may look pretty comprehensive, it should be kept in mind that it does not contain every possible interval. Other than the tritone, no augmented or diminished intervals are included. Because of these additional possibilities, some intervals with the same number of semitones may have different names. A few examples of such enharmonic intervals are given below.
Note that the augmented unison and the minor second both have 1 semitone, the major second and the diminished third both have 2 semitones, the augmented second and the minor third both have 3 semitones, and so on. Thus, there is not a one-to-one correspondence between the number of semitones and the interval name. You will always need to consider the numeric size of the interval as well as the number of semitones it contains. For instance, an interval containing 2 semitones will be a major second if it is written as a second but a diminished third if it is spelled as a third. If you plan to use the semitone chart, use it with caution!
The White-Key Intervals
I. Seconds
The example below provides all of the possible seconds using only the white keys on the piano. Here we see that there are only two seconds that are naturally minor: the minor seconds above E and above B. These are the two locations on the piano where there are no intervening black keys. All other seconds are naturally major. Although it is not difficult to count the number of semitones in seconds, just remembering the location of these two half-steps will make identifying and spelling seconds easier.
II. Thirds
The example below provides all of the possible thirds using only the white keys on the piano. Here we see that three of the thirds (those formed over C, F, and G) are naturally major and the rest are naturally minor. This is an important observation that we will use later when we learn about triads: thirds over C, F, and G are naturally major.
III. Sixths
The example below provides all of the possible sixths using only the white keys on the piano. Here we see that three of the sixths (those formed over E, A, and B) are naturally minor and the rest are naturally major. In other words, sixths over E, A, and B are naturally minor.
IV. Sevenths
The example below provides all of the possible sevenths using only the white keys on the piano. Here we see that there are only two sevenths that are naturally major: the major sevenths above C and above F. All other sevenths are naturally minor. Another way to think of this is to ask yourself "How close is this seventh to a perfect octave?" The sevenths above C and F are only one half-step smaller than a perfect octave, making them major. The minor sevenths are a whole-step smaller than a perfect octave.
Applying the White-Key Method
Now let's apply the observations we have made about white-key intervals to four examples. To apply the white-key method, we compare the given intervals to the underlying white-key interval. Let's review the two basic steps in this approach:
- First, ignore the accidentals (if any). What is the quality of the underlying white-key interval?
- Now add the accidentals back in to determine how they affect the quality of the white-key interval. Do they make the interval larger or smaller?
Remember also that if the same accidental is added to both pitches of an interval, it does not change the size or quality of the interval, so we can ignore both accidentals when determining the quality of that interval.
I. Seconds
If you were given the interval from B to C#, you would compare it to the white-key interval B to C. This is one of the two naturally occuring minor seconds. B to C# would be one semitone larger than this, making the interval a major second. Click "Show Me" in the example below to see this illustrated.
Identifying the interval from B to C#
Identifying the interval from B to C#
II. Thirds
Consider the interval from F to A♭. First, we ignore the A♭ and evaluate the white-key interval F to A. F is one of the three pitches over which we naturally get major thirds. F to A♭ is one semitone smaller than this major third, making the interval a minor third. Click "Show Me" in the example below to see this illustrated.
Identifying the interval from F to A♭
Identifying the interval from F to A♭
III. Sixths
Now consider the interval from A♭ to F♭. Since there are flats on both pitches, we can safely ignore both accidentals and evaluate the white-key interval from A to F. A is one of the three pitches over which we naturally get minor sixths. Since both pitches are altered similarly, these accidentals will not alter the size or quality of the interval, so A♭ to F♭ is also a minor sixth. Click "Show Me" in the example below to see this illustrated.
Identifying the interval from A♭ to F♭
Identifying the interval from A♭ to F♭
IV. Sevenths
If you were given the interval from F# to E, you would compare it to the white-key interval F to E. This is one of the two naturally occuring major sevenths. Does the F# make the interval smaller or larger? It is one semitone smaller, making the interval a minor seventh. Click "Show Me" in the example below to see this illustrated.
Identifying the interval from F# to E
Identifying the interval from F# to E
Note that it may initially take a bit of time to memorize the underlying white-key intervals, but doing so will make it possible to identify intervals much more rapidly and efficiently.
Spelling Major/Minor Intervals
The white-key approach will also work for spelling major/minor intervals, if we restate the two steps as follows:
- First, write down the corresponding white-key interval and determine its quality.
- Next, add accidentals to the white-key interval to make it larger or smaller, as needed.
For example, if you were asked to spell a major third above the pitch E, you would first write the white-key interval E to G. What is its quality? Only thirds above C, F, and G are major, so the third above E would be minor. Since you were asked to spell a major third, you need to make the interval one semitone larger. The pitch E was given, so you should not change it. Instead, you should raise the G to a G# to create a major third. Click "Show Me" in the example below to see this approach illustrated.
Spelling a major third above E
Spelling a major third above E
Now what if you were asked to spell a diminished seventh above the pitch C#? Using this method, you would first write the white-key interval C to B, which is one of the two major sevenths. Since we need the bottom note to be C#, we will raise it now. What effect does this have on the underlying white-key interval? It makes the interval a half-step smaller than major, so we have a minor seventh. We are not done yet; we still need to make the interval one semitone smaller. Lower the B to B♭ and we now have a diminished seventh over C#.
Spelling a diminished seventh above C#
Spelling a diminished seventh above C#