The opposite of a perfect fourth is a perfect fifth.
In music theory, the "opposite" of an interval is typically referred to as its inverse or complementary interval. An interval and its inverse together span a full octave. This means that if you take an interval and then add its inverse, the total distance covered will be an octave.
For example, starting from a note like C, moving up a perfect fourth brings you to F. To complete the octave, you would then move from F up to the next C. The interval from F to C is a perfect fifth. Thus, a perfect fourth and a perfect fifth are inverses of each other because their combined span equals an octave.
Understanding the Perfect Fourth
A perfect fourth is a fundamental musical interval spanning five semitones. It is commonly abbreviated as P4. Historically, this interval has also been known by the name diatessaron. It is considered a consonant interval, meaning it sounds stable and pleasing to the ear.
The Inverse: Perfect Fifth
The interval that serves as the inverse of a perfect fourth is the perfect fifth. A perfect fifth spans seven semitones and is also a highly consonant interval. It is widely used in harmony and composition due to its strong, stable sound.
Here’s a summary of the relationship:
| Musical Interval | Inverse Interval |
|---|---|
| Perfect Fourth | Perfect Fifth |
This inverse relationship is a key concept in understanding musical intervals and their construction within the octave. For more detailed information on this fundamental interval, you can explore resources like the Wikipedia article on Perfect Fourth.
