If a baby is certainly one that heard before, like playing the piano, was seen near the keys, is to ask to portray on the instrument the bird, he will begin to rapidly iterate through the keys on the right side of the keyboard, to get high-pitched sounds. If he needs to show the roar of the bear, he will move to the left and will be pushing the low, bass keys. So we called it the word low, high, characterizing one of the basic properties of sound. Property is the height.
The piano is especially good to understand it: very clearly. Press left, that is "below". The lower notes have agreed to call the "thick" sound. They like the sound Foundation on which is built all the music building.
Move gradually to the right, or, as they used to say the musicians up on the keyboard. Indeed, there is a feeling of ascent, ascension, enlightenment. You've heard the lower and upper sounds, heard the difference between them.
Now open the lid of the piano. You will see that the strings in it are not the same. Of course, you noticed that the piano a form similar to the wing. In accordance with this form are its strings: left long, the farther to the right, the shorter. In addition, those strings that correspond to the lower sounds thick and twisted so-called thread, and the upper is a thin.
The length and thickness of the strings depends on the height of the sound that it can be retrieved. If you try to formulate a more General rule, the pitch is the result of the oscillation frequency of the sounding body. But the frequency and depends on the length and thickness. Try to pull the string and pull her finger: get sound. Now do the same with twine. Heard the difference?
Pitch - is the physical property. It will be measurable. Thus, the tuning fork (read about it in this section), the publisher of the note La of the first octave, gives 440 vibrations per second.
You probably know that the human ear can perceive not all sound vibrations. There are sounds so high that we don't hear, although some animals have produced them and, of course, perceive. These sounds correspond to fluctuations of more than twenty thousand per second. This is already an area called ultrasound. Ultrasound is used in industry and medicine.
Some composers have now started to use a very low sound, almost too not perceived by the human ear as sound. They occur when fluctuations less than sixteen per second. You ask, why to use them, if they still do not hear? The fact that these very low vibrations - they are called infrasound, although not audible, but still perceived by us. They affect the nervous system, the mind, creating a sense of anxiety, fear. Only you should use them very carefully, or they can even be the cause of unhappiness.
The pitch of written notes on a stave. In order to be able to read these entries, invented a system of so-called keys. About this you can read in the stories of "Note" and "Key".