Why is a note counted twice in an octave but not when counting semitones?



Asked by: Steve Severson

The major scale itself only has seven unique notes, but the within an octave, the first gets repeated, so you end up with eight. So it seems that there’s a small error in your count of semitones, and a slight misunderstanding of the relationship between an octave and a scale.

How many semitones does an octave have?





12 semitones

A chromatic scale defines 12 semitones as the 12 intervals between the 13 adjacent notes forming a full octave (e.g. from C4 to C5).

Why is it called an octave if there are 12 notes?

This is called octave equivalence. And is why notes an octave apart are given the exact same name as each other for example a and a the interval of an octave is also the simplest.

Why are there 8 notes in an octave?

The most harmonious interval between notes we hear is the octave, i.e. two tones played eight notes apart. In what is known as ‘octave equivalence’, notes that are eight tones apart have the same name, and roughly sound ‘the same’ to the human ear, but just in higher or lower versions.

Why are notes not evenly spaced?





The musical scale is based on our perception of frequency, and harmonic relationships between frequencies. The choice of 12 evenly spaced notes is based on the so-called circle of fifths. Frequencies that are harmonically related tend to sound good together.

Why are there 12 semitones in an octave?

The idea behind twelve is to build up a collection of notes using just one ratio. The advantage to doing so is that it allows a uniformity that makes modulating between keys possible.

Why is an octave double the frequency?

In terms of physics, an octave is the distance between one note and another note that’s double its frequency. For instance, the note A4 is the sound of a vibration at 440 Hz. The note A5 is the sound of a vibration at 880 Hz. Going in the other direction, the note A3 is the sound of a vibration at 220Hz.

Why do musical notes end at G?

It's just a vibration of air at a fixed frequency measured in hertz.

Why do scales have 7 notes?

The tradition from which western music derives began with filling in the most obvious stopping places in one octave. And if you go by that process it’s easy to end up with seven, but no more. The next pitch is called the octave because it’s the eighth note (just as an octopus has eight legs).



Why do musical notes repeat?

In music, a repeat sign is a sign that indicates a section should be repeated. If the piece has one repeat sign alone, then that means to repeat from the beginning, and then continue on (or stop, if the sign appears at the end of the piece).

Why is an octave called an octave?

Dividing the Octave into Scales



The word “octave” comes from a Latin root meaning “eight”. It seems an odd name for a frequency that is two times, not eight times, higher. The octave was named by musicians who were more interested in how octaves are divided into scales, than in how their frequencies are related.

Why do two notes an octave apart sound the same?

When two musical notes are an octave apart, one has double the frequency of the other yet we hear them as the “same” note – a “C” for example.



Who decided the musical notes?

Guido d’Arezzo

The founder of what is now considered the standard music staff was Guido d’Arezzo, an Italian Benedictine monk who lived from about 991 until after 1033.

Why is C not called a?

The C major scale has no sharps or flats, this scale was created before the piano. When they created the piano (or whatever similar instrument before) they wanted all the sharps and flats to be on the black keys. Since there are no sharps or flats in CM it became the one with no black keys.

Who invented music?

They usually put forward several answers, including crediting a character from the Book of Genesis named Jubal, who was said to have played the flute, or Amphion, a son of Zeus, who was given the lyre. One popular story from the Middle Ages credits the Greek philosopher Pythagoras as the inventor of music.



Why is a called a in music?

So A, the first letter of the alphabet, was, quite intuitively, just a name he used to label the lowest tone in this range. Though eventually the Boethian “A” coincided with our modern “A”, and that is where the philosopher put it first, it didn’t always necessarily signify the note we call A nowadays.

Why is it middle C and not middle a?

However, middle C is not called middle C because it is in the middle of the piano. Middle C is called middle C because it is in the middle of the grand staff, the combination of treble and bass clef that piano music is most commonly notated on!

Why does the piano start on a?

If you play A minor, you are likely to play the lowest note of a piano. This means that it helps us to emphasize the mood of a piece we are playing, without straining our fingers or making mistakes. That is the most important reason why the piano starts with an A while it ends with a C.