A
harmonic sound is said to have a
missing fundamental,
suppressed fundamental, or
phantom fundamental when its
overtones suggest a
fundamental frequency but the sound lacks a component at the fundamental frequency itself. The brain perceives the
pitch of a tone not only by its fundamental frequency, but also by the periodicity implied by the relationship between the higher
harmonics; we may perceive the same pitch (perhaps with a different
timbre) even if the fundamental frequency is missing from a tone.