Frequency renders a perceptual effect that we are all familiar with in our day-to-day lives.  In fact, it is the property of frequency that contributes, for instance, to the intelligibility of speech, as well as forming an important aspect of the informative dimension of music.

In the following example, you will see a piano keyboard depicted.  Click on the Start PlayList 1 button to hear a sequence of sounds, each sound in the sequence higher in frequency than the previous.  You will notice that the higher the sound, the further along the right side of the piano keyboard its corresponding key is.