Pitch

The perceived frequency of a sound (as opposed to the objective measurement of frequency as measured by a frequency counter or oscilloscope). Several psychoacoustic phenomena exist which can cause the pitch, as perceived by the human ear, to differ from the actual frequency. Sometimes, if the fundamental is weak compared to an even-numbered harmonic (particularly the second or fourth harmonics, which are octave intervals of the fundemental), the ear may perceive the prominent harmonic as being the fundemental. Many three-dimensional percussion instruments such as bells and chimes present a more complex case. Spectrum analysis for these instruments usually shows a mix of tones which are not all harmonically related. This mix can fool the ear into hearing a fundemental tone which is not actually present. (This is why the sounds of these instruments are particularly difficult to imitate with conventional synthesis techniques, but can sometimes be created with non-harmonic techniques such as amplitude modulation and ring modulation.)