Third
In music one third is one interval between two notes separated by three degrees.
There is one major third and one minor third.
Major third
major third is the interval separating two sounds of which them frequencies fundamental are in the ratio from 4 to 5, when it is pure. It is an interval of two tone.
Thus, if a note is defined C to 528 Hz, its higher major third semi has a frequency of 660 Hz. It acts of the value of a major third pure, because the report/ratio is very different in equal temperament : this same semi will then have a frequency of 665 Hz.
The major third, at the pure state, show characteristics acoustics remarkable: (ex: C 3 - mid 3).
- its resulting is the note of bottom, two octaves below (C 1).
- The first harmonic commune is the note top, two octaves with the top (mid 5).
- At the pure state (5/4), one beat by low intensity enriches its sonority, had with the friction of one semitone between the 4E harmonic of the lower note (C 5), and 3E harmonic of the higher note (if 4).
- One triad composed of a pure third by 2 the audible speed of the beats of the fifth will divide, by the conjunction of several beats.
These elements confer with this interval a great sound balance, full, clearly, and soft at the same time. This is why the pure major third is the base of temperament mesotonic. The major third is the interval more deteriorated by the passage at equal temperament. In this modern temperament, it sounds very differently. Its fundamental beat is then rather fast, and the sound becomes more aggressive. This is why minor harmonies, who remain soft (see low), are so frequent in the romantic music.
The major third plays an essential part in Western music. The major agreement "fundamental - major third - fifth "(for example C-semi-ground) is indeed regarded as more consonant of all. This is why one it appellle commonly "triad".
Minor third
minor third is the interval separating two sounds whose fundamental frequencies are in ratio from 5 to 6, when it is pure. It is an interval of a tone and half.
Thus, if a note is defined C to 528 Hz, its higher minor third E flat has a frequency of 633,6 Hz - is a ratio of 1,2. It acts of the value of a pure minor third, the report/ratio being rather different in equal temperament : this same E flat will then have a frequency of 627,9 Hz.
If thus the major third is strongly increased by the equal temperament, the minor third is for its part decreased by as much, what does not have the same incidence. It is indeed interesting to notice the existence of a second natural type of pure minor third, anecdotic, in the series of harmonics : report/ratio 6 to 7. That can explain why the ear is less sensitive to the accuracy of the minor third, accepting heights variables of notes.
The minor third is the base of temperament with pure minor thirds - far from used because of its fifths enough grinçantes.
The minor third plays, in the minor triad, the same role as the major third in the major triad.
See too
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