Use the mouse or keyboard to play the music: SD GHJ ZXCVBNM Z: C Note, X: D Note, etc. It produces an auditory illusion that the sound matches the octave you wanted to play in mind.
The sound files used for each key are generated by mixing the sine waves of the note in different octaves with different amplitude according to the difference between the note and middle C (similar to how Stepard Tone works). Stephard Tone: https://en.wikipedia.org/wiki/Shepard_tone Piano Keyboard Vector Image: https://upload.wikimedia.org/wikipedia/commons/1/15/PianoKeyboard.svg
