A harmonic spectrum is a
spectrum
A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of color ...
containing only frequency components whose
frequencies
Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from '' angular frequency''. Frequency is measured in hertz (Hz) which is e ...
are
whole number multiples of the
fundamental frequency
The fundamental frequency, often referred to simply as the ''fundamental'', is defined as the lowest frequency of a periodic waveform. In music, the fundamental is the musical pitch of a note that is perceived as the lowest partial present. I ...
; such frequencies are known as
harmonic
A harmonic is a wave with a frequency that is a positive integer multiple of the '' fundamental frequency'', the frequency of the original periodic signal, such as a sinusoidal wave. The original signal is also called the ''1st harmonic'', ...
s. "The individual partials are not heard separately but are blended together by the ear into a single tone."
[Benward, Bruce and Saker, Marilyn (1997/2003). ''Music: In Theory and Practice'', Vol. I, p.xiii. Seventh edition. McGraw-Hill. .]
In other words, if
is the fundamental frequency, then a harmonic spectrum has the form
:
A standard result of
Fourier analysis is that a function has a harmonic spectrum if and only if it is
periodic.
See also
*
Fourier series
A Fourier series () is a summation of harmonically related sinusoidal functions, also known as components or harmonics. The result of the summation is a periodic function whose functional form is determined by the choices of cycle length (or '' ...
*
Harmonic series (music)
A harmonic series (also overtone series) is the sequence of harmonics, musical tones, or pure tones whose frequency is an integer multiple of a ''fundamental frequency''.
Pitched musical instruments are often based on an acoustic resonator s ...
*
Periodic function
A periodic function is a function that repeats its values at regular intervals. For example, the trigonometric functions, which repeat at intervals of 2\pi radians, are periodic functions. Periodic functions are used throughout science to d ...
*
Scale of harmonics
*
Undertone series
References
{{Signal-processing-stub
Functional analysis
Acoustics
Sound