Final answer:
A complex pitch has no single dominant frequency but includes a cluster of frequencies. Pitch perception is related to frequency and differs from intensity, with humans capable of distinguishing two sounds if their frequencies vary by at least 0.3%. The unique ability to identify musical notes without reference is called perfect pitch.
Step-by-step explanation:
A complex pitch has no single dominant frequency, but a cluster of frequencies that can best be imitated rather than 'sung.' Pitch perception is directly related to frequency and is not greatly affected by other physical quantities such as intensity. For humans to be able to distinguish two separate sounds, their frequencies must differ by at least 0.3%. For example, we can notice the difference between frequencies of 500.0 and 501.5 Hz. This ability to discern differences in pitch is termed relative pitch. The uncommon ability to identify musical notes by ear alone, without any reference note, is known as perfect pitch. Turning up the volume on your stereo will not change the pitch of the sound, because pitch does not depend on intensity. Sound with a lower frequency is perceived as having a lower pitch, and pitch is a key component of musical notes and the music they constitute.