12 scale piano 
You will hear a sound when you click on the keyboard
12 equal temperament scale
Sine wave by using the frequency will also be the sound of any height, but you can play the music to use a sine wave by going to change the height of the sound thinking about "scale".
General music will be played in accordance with the "12 equal temperament scale". 12 equal temperament scale, it is constructed from a height of 12 sounds per octave, the ratio of the height of the adjacent sound becomes 1.0595 times, one octave higher becomes the frequency is exactly twice.
In the case of 12 equal temperament scale, the height of each of the sound, is represented by a combination of numbers representing the alphabet and range that represents the sound name. As an example, represents the sound of [A] is "La" but, 440Hz is A4, 1 octave lower than 220Hz it will be A3.
