Effect

While the impact of accidental alteration exerted on any note of the same name and same height in so far as it is placed, the effect of constitutive alteration is permanent : throughout the range, it's exercises over all notes of the same name of different height but of course, if in the meantime came a change of key signature, or simply an accidental alteration modifying the pitch concerned.

• Eg :

In the example above, the E (flat constitution) affects all the notes, except notes No.4 and No.6 because of accidental naturals. Note No.5, although also a E is not affected by the E because it is situated at an octave different.

Function

The constitutive alterations serve to transpose the scale diatonic natural. Thus, regardless of the key signature, you will always find in each octave, "two diatonic semitones isolated framing alternately two and three tones".

"Transpose a melody" means "move this song in height, without altering its constitution". When transposing the names of notes change, but the intervals between notes are unchanged, thereby avoiding distortion of the original melody. If the spouses intervals of the diatonic scale were identical, transposition does not deserve a long explanation. But as we know, these intervals can be either tone or diatonic semitones, it is essential to retain alterations to the exact distance from these intervals is not changed during implementation.

• Thus each key signature set its own scales and its own tones . For more details on the key signature and their significance in relation to the key of a song.

• Transpositions of the diatonic scale natural:

Change key signature

Just as the quantification of the measure, or as the key, the key signature can be changed in the course of a song. This is called : change of key signature. In the case of a change of key signature, all the constitutive alterations may contain naturals. A change of key signature can occur at a modulation .