Interval (music)

Music has different sounds.

Some sounds are high. Some sounds are low. An interval is the space between two sounds.

Some sounds play one after another. This is a melody. Other sounds play at the same time. This makes a chord.

We use names for these spaces. We can call them a third or a fifth. We also use words like major or minor. These words tell us how the sounds feel.

A small space is a semitone. A larger space is a whole tone.

These steps help build a scale.

Music uses these steps to make songs. It is a way to build beautiful sounds.

An interval is the distance between two musical sounds.

We can hear intervals in two ways. A melodic interval happens when notes play one after another. A harmonic interval happens when notes play at the same time.

Musicians use special names for these distances. They use a number and a quality. The number tells us how many notes are in the space. For example, B to D is a third. This is because you count B, C, and D. The quality uses words like major, minor, perfect, or diminished. These words tell us more about the sound.

Some intervals sound very smooth. We call these perfect intervals. These include the unison and the octave.

Other intervals might sound different. A semitone is the smallest step in most music. Two semitones make a whole tone.

Scientists can even measure these spaces using cents. This helps people compare how big an interval is. There are 1200 cents in one octave.

An interval is the distance in pitch between two musical sounds.

Musicians experience these distances in two main ways. A melodic interval happens when notes play one after another in a sequence. This is like a melody moving through time. A harmonic interval occurs when notes sound at the exact same time.

This creates a chord or a stack of sounds. Understanding these distances helps us understand how music is built and felt.

There are many ways to measure the size of an interval. One way uses frequency ratios to compare the two sounds. For example, an octave has a ratio of 2:1.

This means the higher note vibrates twice as fast. Some systems use small-integer ratios, like 3:2 for a perfect fifth. These are called just intervals or pure intervals. Another common way to measure is using cents.

There are 1200 cents in one octave. In the common 12-tone equal temperament system, one semitone is exactly 100 cents.

Music theory uses a special naming system for these intervals. Every name includes a number and a quality. The number tells you how many letter names or staff positions the notes cover.

If you go from B to D, you count B, C, and D. This makes it a third. The quality is a second part of the name. It uses words like major, minor, perfect, augmented, or diminished. These words help musicians know exactly how the notes are spelled.

Different qualities change how an interval sounds to our ears. Perfect intervals, like the unison or the octave, are often considered very stable.

Other intervals might be described as major, minor, augmented, or diminished. For example, a major third and a minor third are different sizes.

An interval can even be very small. A semitone is a small step. Even smaller steps are called microtones. Some are so small they are called commas.

Intervals help us connect different musical ideas together. When you join two intervals, they form a new, larger interval.

If you stack two thirds, you might get a fifth. This is because the number of the new interval is one less than the sum of the parts. This math helps musicians build complex scales and beautiful harmonies. By learning these patterns, we can see how simple notes turn into great songs.

In music theory, an interval is the difference in pitch between two sounds.

This concept is fundamental to how we understand melody and harmony. When notes are played one after another, the interval is called melodic, or horizontal. This creates a linear sequence of tones. When notes sound at the same time, the interval is called harmonic, or vertical. These simultaneous notes form chords. Understanding intervals allows musicians to navigate the relationships between different pitches.

Physically, an interval is the ratio between two sonic frequencies. If you compare the frequency of one note to another, you find a mathematical relationship. For example, any two notes separated by an octave have a frequency ratio of 2:1. This means the higher note vibrates twice as fast as the lower one. Because the human ear perceives pitch as a linear increase, but frequency actually increases exponentially, musicians use different measurement systems. One common unit is the cent. The cent is a logarithmic unit used to compare interval sizes more easily.

There are two primary ways to represent the size of an interval. The first method uses frequency ratios. In a tuning system known as just intonation, intervals are expressed by small-integer ratios. These are called just intervals or pure intervals. Examples include a perfect fifth at a 3:2 ratio or a perfect fourth at 4:3. However, most modern instruments use 12-tone equal temperament (12-TET). In this system, the ratios are not simple integers. For instance, an equal-tempered fifth has a ratio of approximately 1.498:1, which is very close to the pure 3:2 ratio.

The second method uses cents to provide a standard scale for comparison. In 12-TET, the distance between an octave's lowest and highest frequency is divided into 1200 equal parts. Each part is one cent. In this specific tuning system, every semitone is exactly 100 cents wide. This allows musicians to precisely measure the distance between any two notes.

Western music theory uses a specific naming scheme for intervals. Each name combines a number and a quality. The number, or diatonic number, indicates how many letter names or staff positions the interval encompasses. For example, the interval from B to D is a third because it includes B, C, and D. This is an inclusive count, meaning you start counting at one with the first note.

If you add accidentals to the notes, the interval number remains the same. This is why the system is often called diatonic numbering.

The quality of an interval is defined by terms like perfect, major, minor, augmented, or diminished. These modifiers describe the specific character of the interval. Perfect intervals, such as the unison (P1), fourth (P4), fifth (P5), and octave (P8), are traditionally viewed as highly consonant.

Other intervals are categorized differently. Major and minor intervals are often called imperfect consonances. If an interval is widened, it becomes augmented. If it is narrowed, it becomes diminished.

Intervals can also be categorized by their size relative to an octave. A simple interval stays within a single octave. When an interval spans more than an octave, it is called a compound interval. The quality of a compound interval is determined by the simple interval it is based on. Additionally, musicians work with intervals smaller than a semitone. These are known as microtones. Some of the smallest microtones are called commas, which describe tiny discrepancies found in certain tuning systems.

Finally, intervals serve as the building blocks for complex musical structures. When you join two intervals together, they form a new, larger interval. Interestingly, the number of the resulting interval is always one less than the sum of the two original numbers. For example, joining two thirds results in a fifth rather than a sixth.

This mathematical logic allows musicians to stack intervals to create scales, chords, and sophisticated harmonies that define different musical styles.