ABSTRACT
When people listen to a complex tone, such as that played by a musical instrument, two attributes of the sound are immediately apparent. First, the loudness of the sound is an attribute closely related to the energy or acoustic power of the waveform. Second, they hear the pitch of the note that the instrument is playing. A periodic waveform is one that always repeats itself after some interval of time. The time interval is called the period. The reciprocal of the period is called the fundamental frequency. The fact that the pitch of a sound can correspond to a fundamental frequency that is not present is called the problem of the missing fundamental. The pitch is invariably equal to the fundamental frequency. This class of waveforms is basically uninformative about how pitch is perceived. According to place theory, the acoustic stimulus undergoes a limited frequency analysis caused by the mechanical resonance properties of the cochlea.
