Stretching (music)

Under stretching or spreading , engl. stretch-tuning , refers to a technique in the voices of stringed instruments , especially pianos .

When tuning the piano , the temperature is first set, usually in the form of a circle of fifths from the note a ¹ , then you tune up and down in octave steps. The octaves are "stretched", that is, the upper notes are tuned higher and the lower notes lower than they would be mathematically.

Although the fundamental vibration of the strings is “wrong”, the human ear hears octaves with little or no beating. This is due to the fact that the overtones , which make up a large part of the sound of a string, only correspond to the arithmetical ideal (1: 2, 1: 3, 1: 1: 2, 1: 3, 1: 4 etc.) would correspond. The stiffness of the real strings, however, exerts a force on the strings in addition to the mechanical tension and thus increases the frequency of the overtones (the higher, the more) - the overtone sounds higher. With extremely short and thick strings, this effect is so strong that they sound unclean on their own and are practically un-tunable. This phenomenon is called inharmonicity .

The amount of stretch depends on the strings; the stiffer a string, the more the octave has to be stretched. With a long concert grand piano (with relatively long and therefore less thick bass strings), the octaves are stretched much less than with a low piano . With a harpsichord with its thin strings, the octaves are not stretched at all.

The degree of stretching still determines the human ear and not the electronic tuner , which is, however, a very valuable aid in creating the various types of moods . The stretching affects the whole instrument, more in the deepest bass and upper treble, less in the middle.

For the purpose of approximation to real pianos, electronic instruments are sometimes "detuned" in this way, although this is actually superfluous with their type of sound generation.

Inharmonicity can also help disguise minor mood disorders in a manner similar to what vibrato does with other instruments and singers.