| The human ear is capable of hearing over wide range of sound pressure (loudness) and frequency. |
| It seems that in order to maintain sensitivity where we need it most, our perception of sound, in the broadest sense, has evolved to be roughly logarithmic. |
| The term pitch refers to our perception of musical sound. |
| It is generally tied to the fundamental frequency or, that is to say, the longest wavelength associated with a given musical note. |
| The grand piano has 88 keys with corresponding fundamental frequencies of approximately 28 Hz (A0) to 4200 Hz (C8). |
| Consistent with our logarithmic sense of perception, we hear the doubling of a fundamental frequency as the same note, only higher in pitch. |
| This doubling in frequency is referred to as an octave. |
| The grand piano has a range of just over seven octaves. |
| The sense of equivalence between notes that are an octave apart is effectively demonstrated through an aural illusion known as Shepard Tones in which a series of discreet tones appears to rise without end. |
| The continuous version of this illusion is called a Risset Scale. |