Sunday December 6, 2020, 00:09
Usual musical instruments produce the sound through percussion, air or rope. Today we have to add the electronic. Under that of air, the organ emphasizes, a complex instrument in a box that is usually an artistic jewel in itself. There is news in ancient Greece (s. III AC). Until the 20th century, the organ was completely mechanical and manual. In this century the pneumatics, electronics and electric motors were included. Under the components we will emphasize the following: the pipe, formed by tubes that are usually built with metal or wood. As far as their shape is concerned, they can be cylindrical, conical or rectangular and open or closed. In modern organs there are pipes with 32,000 tubes. This allows many possibilities to mix sounds and explain the wealth and variety of sound color (BEL). They are called manually and pedalo after the set of keyboards that are touched by hand or foot. There are organs with a maximum of 7 manual keyboards. The type of sound or bell is selected with the records above the manual or on the side walls. The sound is reached by relieving air in the tubes by means of bellows. They used to be treated with the help of various mechanisms that were replaced by electric motors from the 19th century. The Bellows Air comes in a box, called Secret, in which the tubes are supported and full of valves and channels. The air inlet in the tubes is produced by pressing the hand or foot keys. The pulsation, by means of a mechanical system that is called action, which is vertical movements in horizontal turnover, opens the air inlet valve to the tubes. These mechanisms became tires and currently electronic. From all this complexity we will see how the tubes produce sound.
The organ has two types of tubes whose effect is comparable to those of other wind instruments: that of smoke (lipstick) and the tongue (lingual). Moreover, it has an extensive range of sounds: the flute, the viola, the trumpet … and even the human voice. The sound quality or tube bell depends on many factors. When they are open or closed and their shape, diameter (width) and length. In addition, in smoke pipes, the position and shape of the air flow in your mouth.
The sound is produced by longitudinal vibrations of the air columns in the tubes. These vibrations produce the fundamental mode (frequency) and harmonics. The vibrations of the air molecules are maximum (antinode) in the mouth where the air enters.
In the case of closed tubes, for fundamental mode, this vibration damping is up to the closing wall, the vibration is zero (junction). In an open tube, the fundamental frequency has a junction in the middle and two antinodes at the ends. The harmonics, both in closed and open tubes, contain multiples of the number of nodes and antinodes of the fundamental frequency.
